diff --git a/2022/input/day_21.txt b/2022/input/day_21.txt
new file mode 100644
index 0000000..f8f8610
--- /dev/null
+++ b/2022/input/day_21.txt
@@ -0,0 +1,1551 @@
+mvnb: mhgv * zvcm
+nrwg: pqnb + wznq
+mcbv: 1
+vwnl: 15
+ggdz: bgvn + mwjn
+nnmj: snhj * fpmt
+zmzd: ttjq * zrhr
+tdpj: nvdr * mlmj
+mdps: jfrh * spnj
+wmwm: fdcg * pmbd
+qrcq: vrpq + bwpv
+sgzv: 2
+zhrt: 5
+mzwm: lzmq + ldzw
+bwhp: 2
+clfd: 4
+rmwq: 11
+pqtc: srtc * vjhc
+cqrh: bnph * jzrj
+mbjq: 5
+tqdl: rfll + dbhj
+lsbb: 11
+fcld: cgjq * qmbc
+mqvz: 6
+dghz: 8
+qncq: 5
+nsql: csns - lrfq
+qzfg: 2
+wsqv: 1
+vjph: bwwn * qjmh
+dsjq: wnls * pdqm
+tmhv: frmn * cmdn
+pqnf: ljhb * zzdg
+rhmw: bjcm * mqzs
+tgtv: psgh * ndbj
+cqgs: 4
+vthp: 5
+zcfd: ffdn - gwgf
+tsrp: nlbv * ptbr
+cldw: 2
+nmlz: 2
+pjhm: mhvf * cdms
+nmln: dhwj * gfnb
+ldzw: bbls + qwhm
+fljd: rbvm * fprb
+gwhp: jvbm + rrwh
+pjmc: mtrd + wljp
+gnph: crdg + zvqd
+bccm: nctz + fvcp
+gwjj: fclp * fplf
+qsth: wshg * lspl
+ttcl: gpmj * wftl
+ggrv: 3
+bvqd: mdds * jrpz
+nglg: 2
+ddpq: 10
+wflc: svsd - crbr
+mqzs: 18
+vfnf: 3
+lrdw: gfdg + mbjq
+wflw: glbs + vdsg
+jdln: sgln + dsfj
+ddlp: 5
+zcmw: mwnc * mjmp
+cqtt: 11
+rswb: 3
+mhzc: mfsc - mgmb
+shlm: tsrp + pfsp
+hbzq: svrr * vzsj
+tvqp: 4
+plsl: 5
+dfnt: 11
+scvz: 3
+nzjp: bhqt * chtc
+wqst: 14
+vfdd: hccl + vwwl
+rzsp: srcq * jrbl
+ftgb: wmph * jslc
+qplw: pjdw + pmjb
+fqpq: 3
+bdpv: dldq * gptn
+rlpd: fntc - rlsc
+nrlz: 7
+lmph: 4
+zfzv: 2
+hcpp: 3
+sgjg: 13
+rhth: 11
+mgln: 2
+gpjt: 2
+cgjn: 3
+bglm: 2
+hdvr: hqdc + wvrl
+jmdz: tswl + gvcj
+mlmj: wglf - pnwp
+qpdz: dgjl + zrbp
+pczj: gwml + gqzf
+grpd: jdqh - rlqh
+mvbt: qslg * nbfg
+rcsr: 2
+vrsn: 4
+ldrz: 9
+zdtn: 3
+zffh: 3
+wmff: gnph + rpmd
+szgr: whnr + vpsw
+vrch: 15
+jdzq: jnwq + qznm
+wzdt: tnlq * zcjs
+phfl: mhvh * sqds
+zgzd: mqjh * lgdh
+zhfp: 2
+wqvz: gfnw / tdlb
+zrtm: 2
+lhsz: 2
+vncz: jpcs - mpbh
+nmcn: 5
+fzhd: gfps + dfnt
+vpsw: 3
+wbrz: mssm * bwdn
+jrpz: 3
+zzdc: 2
+mdnv: dhzh / stpr
+scrb: twtl * hnts
+pqfz: 3
+zlww: 3
+lcbg: hzwm * lhmd
+wggf: jrmf - fhwg
+vtsc: vlsc * qntj
+mtrd: vfbp * pgqs
+gvjs: jzdl + wbsc
+wfqq: 20
+dwpw: tjvc + bzlq
+fpbv: 2
+rcpc: htgv * nrmh
+hlfw: bcch * fdlh
+blgl: 2
+wwps: pttp + vgbb
+dsfj: 3
+bfqz: prrl * htvb
+bcqm: mtfv + pmzz
+bdnm: 2
+dhsh: 2
+pgfv: bzvl + zwtw
+nrmh: 2
+gpvs: 5
+qrpw: nssz / dctm
+mhgv: lqsc + htbz
+wqbg: 17
+zlbn: gzmw / dnht
+rzsb: nnnv / zdtn
+psgh: 2
+scct: 5
+nvsr: gllj * dcpl
+pmzz: vgmq + cmmb
+qjmh: 5
+llzr: 3
+sfbz: 2
+ttcc: mcbf + zfqv
+phwz: jdnw * lbqf
+swbn: hndd * mqlz
+qbfv: 4
+bsgr: 4
+gjvc: sldt + cbtz
+spjp: vqgq * sjqt
+hcdz: 10
+qhgq: 4
+dbdm: 11
+fjdm: 7
+zcpr: 3
+fplf: htfs * hqpl
+zsjz: 2
+crrp: gtbr + ffdl
+zgzp: 3
+hcfd: 3
+tzqt: jmmc * ddlp
+pvnd: bsjw * qwcv
+vfbp: 2
+jrmf: 10
+zjfl: cplp * qjzl
+sldt: nccd / rqqc
+vrhr: 5
+gbcj: mzwm / qbtb
+pbgg: mvnb + fhvf
+wjjb: 17
+wnlb: 1
+mjhf: tlrc * zshr
+hglg: gmsv - djmf
+wlhn: pbzp * sqsz
+lldd: zsqz + pgqf
+drmf: 4
+whfl: 3
+prln: 5
+zwll: blgl + jhjl
+frqg: hcqt * lmnm
+qhld: 5
+vdql: 4
+srrm: grcq * lhnc
+gtcf: 4
+lrfq: 4
+nftt: fghr * zmrv
+nbnn: 3
+ztsb: 2
+zcjs: 12
+rcvz: dwgv + zffh
+jcrg: 4
+csmf: sdrs + jngq
+sjbs: 2
+hqpv: 2
+mrnr: wtwh * vpwt
+vqgq: 19
+znln: 2
+rhff: mrsq * rdzz
+fplg: 3
+sjsn: lqvb * csqw
+qntj: 2
+hqhq: pmqg + bcqm
+pclp: llzr * lhzl
+jhrn: sfvv * ztrh
+jhvn: hlbn + gvcw
+hthb: 3
+cmmb: trnb - vpst
+qbsb: 2
+mqwl: hfrf + rhmw
+tzwt: 4
+bqvp: 5
+mrsq: 2
+dmzp: nzjp + bflc
+cszc: 5
+tmzb: 9
+qvnb: bvcg * ndzl
+tptp: hqfg * hwns
+snwq: 7
+fwfp: zttd * lsbb
+rgfr: zdmc * shpg
+qnpc: fmgg * ptwc
+bpfq: pgdg * djnb
+mzhc: 4
+pgdg: mjqg * gjnm
+wzzh: stll - lvdf
+prcd: mmzq * lrdw
+chjs: 16
+tfnc: fjdm + rzsb
+jdnw: gcln + llpl
+mljm: 12
+vjdj: sjsn * lmtb
+zprg: fwfp + nrzs
+pgqf: 1
+pgbv: 3
+gzjv: 2
+bpff: dhww * dwlc
+zsnd: 2
+vjhc: lrhg - hzps
+sjrq: 2
+qsdt: pbrm * nbpg
+prrl: 2
+mlnv: 3
+tglc: 1
+gssc: hwrj + wlhn
+rrrv: 4
+zpqf: 6
+slwd: 8
+bnnb: scvz * rcsr
+rmwn: 3
+nvdr: 2
+cwcp: qrpw + hglg
+pmjb: 15
+pmbd: wcbz - zmsb
+hvvj: dfqf + sssf
+dzhc: dprs * pclp
+dwlc: mcbv + zmzd
+zmcl: 19
+zmnh: mgbq * djzw
+zjjh: 2
+mczw: lzrq * thpr
+gzmw: nbjs - rchf
+cfwb: 3
+fdhh: 4
+swqs: 2
+swrp: 5
+mgmb: ghrf + jqrz
+hcqt: jlbp + dcmn
+bzwg: 3
+mfqj: slhj * pftp
+zmrv: 4
+jmls: 19
+gpmm: wwmw + bwdr
+nzmh: pfvz * hwhs
+dqnz: 3
+dvfs: 2
+qgfv: 4
+dbjg: nvzf + rhzd
+fvvg: 18
+fmsm: 19
+qlfl: 1
+wsmh: 20
+crdg: nwbc * vnsj
+gwgf: 2
+ltzc: 4
+rrjh: 8
+wljp: pjhm * fvnf
+phzl: bffw + ssfh
+vjqj: clvq + lpjz
+lgdh: 3
+wshh: 2
+lvbv: 2
+rqhb: bpfq * pdmt
+rpjp: 11
+gmbv: lgvw + dhsh
+pdtl: 4
+mqlz: wbvz * dsfc
+pfgm: nrhm + glwz
+cpmj: 13
+mgzc: 5
+mhvh: 6
+rdsw: 5
+wvqm: 3
+trcj: dlgv * sjbs
+wnzm: 4
+trcv: nhvd + wsmh
+zbcq: 2
+rjdj: rhgh + wwrv
+pvfg: 4
+lgcg: 1
+bdzt: crts * bwmt
+mjrc: 2
+swfb: 5
+ghzw: mhlc / lvbv
+pbzp: 3
+vzzn: zvhw * fhfh
+ghsl: bzwg * rfsw
+smmv: 5
+hdth: nttd - sdbc
+qgcb: wshh * hrqb
+dndz: 3
+dwms: 4
+qcqm: 4
+dscj: 2
+svfw: qqsq / cfwb
+jnfs: 2
+vtsb: 6
+ztrh: 2
+lhmd: 3
+lslm: 1
+qmcn: 3
+fzzz: 3
+ndnw: 4
+cmqt: 4
+rhvf: pzpb + jbrm
+rfqf: 2
+tlsm: vcbt * lnpn
+fqvq: 2
+rscb: 2
+jtwb: 1
+lgfc: 5
+qtzt: 17
+pjvb: 8
+tvms: qvdq * qsdt
+nmzq: rswb * bdtq
+nrjr: scrb + wffv
+swcg: mjhq - jmdz
+vzdl: ggcf * jwdm
+fwzb: ztgt + zsjz
+hzzt: 2
+rbwp: 11
+vvcf: 4
+cfbm: jpmr - qtct
+twpz: dvfs * lhsg
+vhgj: 1
+fpdd: 10
+fcws: dfhw / psbh
+fgts: 4
+mmrh: 15
+zwjz: 3
+grdz: 4
+mpwt: 3
+fmjd: 2
+jlbp: hqmw * bnzz
+ssrr: sjlb * gvtg
+jpcs: qshz * chph
+cfrl: cqtt * fjlb
+wtrn: 5
+bzsr: 2
+jzgm: rrrv * tgbv
+jpcf: 4
+nnnv: vnhz * vdql
+cssp: stmf * zrzq
+tcrd: szqt * nsqd
+qdlf: bbnf * vlch
+dhbn: 7
+qqlh: 2
+pnss: pwrd * vtsb
+gdfn: 4
+nrhm: brvj + hcdz
+rbbz: mmft + tglc
+wrqt: 7
+drhp: nzmh + mrdt
+nrtt: rrts * lhsz
+rbhd: lvmz * mzqf
+jtln: 5
+vmjq: bccm / nwph
+jnqt: 6
+vgbb: gpww * jgtw
+pnnc: 2
+jngl: 20
+qmbc: 2
+fqqp: 2
+lsls: 3
+pvwf: fvvg * fsmf
+nsqd: 3
+bdjw: 6
+rwwv: 9
+jqgw: dlwm + wsqv
+mjmq: 7
+drlc: 2
+nwhm: 8
+bdtj: 2
+hfzj: pnnc * vtsc
+rlcd: mcsj + hnnw
+jzrv: vmnt + svth
+jslc: 2
+bsjw: 5
+hszf: cczm * cpbb
+hzrc: 3
+bwmt: 3
+rnbh: brmq * vzjj
+phhl: 7
+zrpw: jwjr * gwsl
+bzvl: dvtn * lfqd
+dtfc: 2
+tmlt: 3
+cgrs: 3
+lqjc: lcps * pbjq
+zzrb: 5
+bdct: 17
+vzsj: sqls + rwrw
+rqfr: cmqt * mpgr
+lvdf: wfrg + mhvz
+rtsv: 2
+rshw: 6
+pdrq: 5
+tgcm: 12
+ltsm: nrjr / gclp
+tvlw: njmh + qrcq
+stjm: 4
+dvch: rhff * zzdc
+wrpg: 5
+qvnz: zlbn + hbzq
+vlfz: 2
+hcqm: 2
+lwwl: 2
+zrzq: 3
+dvtn: dqwj + nbzl
+mdsh: 3
+nlbc: 2
+shgt: prln * zsmq
+cfnm: 12
+lhzl: lwjf / wmmf
+lhrn: 6
+twcj: gwjj - rrbz
+gqzf: spjp * ftlm
+flgw: zzhf * hmpv
+hlzz: 2
+lgvw: 5
+mhvz: sbvs * sbtw
+zpth: 2
+pqnb: twcj / jrfv
+crbb: 2
+mrdf: pjvb + zhrt
+vpwt: dqnw * zsnd
+rfgs: bfnq + bfqz
+vsvp: jpnh + rglz
+vpnq: vlfz * rpjp
+hdrn: 4
+cgjq: lqjc + tgwm
+mpbh: wvqm * scct
+wwrv: wggf * zpth
+nmjz: ltcr * sfbz
+lrql: vmsp + ftgb
+rwrw: bfbd * gftc
+vvbg: lffc * gnwg
+hcfn: jpjr * zbcq
+scqf: 2
+htvb: lgnw / mhzp
+nbzl: 6
+jdsl: 2
+fdcg: 2
+zwct: 2
+bvcg: 2
+bccl: vzqf * cqrn
+wtgl: 2
+vlsc: sgzv + zmgn
+vmdr: 2
+jmwv: 3
+mhbg: fqvq * jjmg
+spnj: 2
+ttjq: nmln / vcdl
+zzzw: ccjr * pvff
+zzhf: vrsn * dlrf
+mmhq: mvwm * hvvj
+mzqf: 4
+nssz: svfw - mczw
+pmpv: 1
+bflc: 1
+vzfq: 5
+nvzv: 3
+fhwg: 3
+vzws: 2
+dlpj: 5
+smsj: lzbf * chjs
+qmrr: qbfv + rbwp
+cjmz: cbvt + phwz
+tnlq: tmnm * swhl
+nsqp: 12
+rpmd: wmsh / bqvp
+hbzl: svhg + cqsd
+jrvm: grdz * rpll
+wvrl: szgr * gsjf
+dbdl: jlnf * vccn
+bwdr: 11
+fddt: wgsc * wgmj
+mtmq: snwq * cqtl
+nvzf: humn - ptcw
+srmq: vhgj + sgjg
+mwzd: nnmq * jlbl
+vpbm: 3
+ljnr: jclm + pfnb
+jrpd: 2
+cdcb: qtzl + mvlz
+pjqr: tfdf + glsj
+nlbn: zwll * hltn
+hpmc: 5
+svhg: lmbs + drbj
+zwzh: 2
+fwzh: 3
+zmwg: 3
+ghrf: nvdh - qzzc
+vjzr: 2
+hptp: dznv * wdrf
+drbj: 2
+ftns: 4
+zrbp: 6
+fpnm: pnss + djzq
+bfpl: 5
+jslh: mqvz + lpcl
+nwph: 7
+pcpc: 2
+cmwj: 9
+vnqc: cwcp * glgp
+gtrn: 5
+lgnw: lrql * csvf
+fwgh: hrss / qqlh
+sbvs: 12
+nmgq: 6
+wcgj: pmdv * nnmj
+gmft: trcv * spsq
+ndtn: 11
+pwrd: 11
+hnnw: nfgf + gcwj
+dvrs: 5
+qjvh: 3
+mmpr: 8
+gswf: hmdf + wrzn
+jznw: bdpv / dsqp
+phdl: wlbb + mszf
+hftr: hcfn * qcrj
+hnts: 5
+glpg: lpwh + nhzf
+root: jwcq + swbn
+nrhc: 4
+cbvt: zdtq + scqw
+vsrf: qtzt * tppm
+fntc: rwlq * fjbz
+dfpc: 3
+dsqp: 2
+qznm: 2
+hzps: zrpw - qpwj
+mjqg: 5
+cbrt: cmwj * qvfj
+hhjc: 2
+jwcq: nrwg * vpgj
+hwcs: rvrb * wfpf
+wzmd: 3
+pdqm: sncw / bbdv
+mmft: fjnb * stqp
+zsvt: wtrn + ggbt
+gsjl: 3
+sjct: lshv * lltl
+wtwh: 18
+jrwd: 2
+bfnq: jhvn + tvvn
+ctlf: 13
+cbtz: dbqb - bdct
+ddjv: zcmw * thvp
+wnls: jngl + rcrs
+pgpt: cbrt + gwhp
+nqhp: 15
+thvp: mfqj + hprt
+cgqj: qzlh + hqhq
+jfhf: 7
+dlgv: 3
+dfhw: wrqt + ncjl
+mpgr: 2
+mqqn: 11
+chph: twpz + vwnl
+jfrh: pgfv * rpfj
+rqgl: vbfg + cgqj
+sszs: 2
+hqfr: hlfw + zlwh
+hzdm: wzmd + dsbm
+wvgz: ftdc + lwvz
+wwbw: rtsv * rqpc
+jzdl: 3
+jmdf: 12
+wmsh: nhbv - ddhj
+nnmm: 2
+nfnv: cgdf * rscb
+mhgr: 3
+cdpg: mzhc * jctl
+jcpn: 2
+sqjg: 3
+whdb: 2
+lbcg: 3
+jqzj: cszc * fnsh
+rfrm: lbvw * jbhn
+czqc: rmwq * tbcc
+qzlh: qnpc + smfj
+mtfv: csdb * htzv
+rwhc: rfrm / sjzl
+qncl: qmcn + jzrv
+zdcb: 6
+ntcs: 4
+rwlq: sbzj + cdpg
+dhww: 6
+sjqv: 2
+lspl: 12
+mvpr: 11
+jpmr: mqlg / nglg
+wffv: swcg * njdn
+jctl: crbb * zzzw
+znvq: 7
+qcrj: 2
+gftc: vjzr * wrpg
+rbvm: 5
+bshl: lttb * jcpn
+jpnh: 10
+qrtr: 2
+qjzl: qmrr + jqhm
+zrtg: 3
+ndzl: 3
+nbhz: vbsv * cfnm
+ctjd: 5
+fhfh: 6
+rrtz: tljt + vnqc
+hqpl: jnfs + ldrz
+srtc: 5
+dchn: fdhh * vfvr
+gjnm: 5
+mcsj: qvnz * fqmp
+smfj: dchn - zdrq
+bhwd: hqhd + vnrz
+wbht: 2
+vpgj: wgtb * prmn
+sjqt: 5
+fjnb: 2
+tfqr: mvbt * znvq
+clrc: 14
+lffc: qlfl + nfnv
+lzrq: tvlw * clfd
+wnjr: 11
+bdtq: 3
+jwvq: gmft + vsrf
+swhl: 3
+vwwl: dlhh * qdwz
+mngd: lcbm + wnlb
+gjzt: vvfw - hdth
+dsfc: cjmz * nmlz
+crbr: 1
+vbsv: 7
+stpr: 5
+blwj: fddt + ntcs
+rwmg: qgfv + bjcd
+dprs: nsql - cqdn
+tlcv: 19
+hqhd: 8
+rtss: lldd * flfc
+wcrn: 2
+flfc: tsqg / mgcb
+grfs: 9
+qwvf: 3
+ghcz: 2
+frmn: 7
+cdtd: 1
+vhqn: 11
+jjpc: 16
+spsq: dphq + tmnv
+hcrb: 3
+lcbm: 6
+ngpm: lsls * tqjw
+srcq: zgzd + qqnj
+pvvz: 17
+prnq: 4
+jbtz: 13
+sbtw: 11
+ccdv: 3
+cqrn: 2
+jlpq: 9
+slhp: 9
+tmnn: ftrz * rfgd
+lpcl: qrtr + dlpj
+shpg: 2
+bbdv: 4
+bwwn: hcfd * pgbv
+jfnb: 3
+rlnm: 4
+rpfj: rtdg + vpjl
+wvhz: dpvd + qdhr
+gwgn: 3
+fsmf: 3
+dbbn: 5
+nvsm: mzcw * wzft
+tfdf: 2
+fmwm: 2
+nswm: 8
+cfqf: cblg + qsth
+sjfw: 3
+slnp: ghzw + bpff
+zbcf: cdmp + nrhc
+vflc: 16
+qdhr: mzqb * hqjm
+zhtm: sbhg * swqs
+dsbm: 3
+vjjf: 7
+jrqb: 9
+zmlb: lqwh * gmnm
+wtdg: 5
+wwmw: qgcb * jtls
+bplb: 3
+brmq: 3
+mtpq: pvnd + pvfg
+nbpg: 11
+djzq: fgts + svsj
+ncjl: sbbm / pmgv
+jmbz: fgtb * jdvn
+zfpj: 3
+hbvq: lsgq + hgsv
+mzqb: gtzg * mtpq
+fbzj: nqhp + nmlv
+vnhz: lcbg - njqm
+jlzb: 4
+sgln: nbnn * zwjz
+bqln: gqqg + tzqt
+gdwh: 3
+pjcw: zgjm * wnzm
+ltgb: 2
+hwns: 3
+ftrz: mjhf / phcr
+jwdm: 2
+qcwb: 17
+jmhl: wmff + cfqf
+humn: 2411
+bvwh: 2
+stmm: 5
+cssw: qcqm * sjfw
+zvrg: 5
+ghzp: 4
+pzpb: 17
+nbfg: 9
+sgml: bglm * vfdd
+sdbc: qlpt + brdb
+mngg: vjjf * wflw
+fqmp: cfvg * swrp
+svsj: wtdg * mvpr
+hqdc: tmzb + gpzw
+phcr: 2
+dbqb: lfmh * glpg
+glgp: 2
+gqmc: sjrq * fccp
+pjrz: 3
+nflq: 2
+trbd: clrc + hmmb
+cwbw: cslb * tfnc
+wglf: wjrj + dwsw
+cnbs: 12
+nlbv: vpnq / zvpt
+qvhs: prng * gpvs
+zrhr: 3
+fmgg: 5
+bfwm: ccdv * gpvz
+mvtj: zmwg * wpfz
+mjhq: dscj * mqwl
+tvvn: wqbz + hzrc
+tgwm: rhgw + wzdt
+ssfh: cwbr + tbzm
+wbvz: jmbz * mhmr
+wjdt: nsqp + zlww
+chnh: 2
+gpqn: vdrt + mdnv
+ctml: 3
+nrfs: 1
+lrhg: gjzt / jtln
+tvlv: 5
+hntz: cpjg + lblc
+pcwb: 3
+jgrz: rwhc - jfbn
+snsh: ttcl + grcp
+fvmg: qhgq * tcqc
+bwpv: wdlg * jcrg
+lwfz: bwwh / pgvf
+llnh: rqhb + hgzw
+lfdz: dvch - hlrh
+zfqv: 6
+nhzn: 17
+tnhj: 5
+jmmc: 5
+rgnp: bqln + jzwq
+rqpc: 11
+zwtw: rbbz * cdcb
+hnzp: 11
+lqsc: 4
+jgqz: mmrh * hcpp
+lqqp: 11
+gbtd: 5
+cjgw: 2
+tdlb: 2
+jcjn: 3
+njmh: 6
+whgw: bgff + qplh
+lbwh: 4
+lqwh: dwrp + tgrf
+hprt: dbjg / hlzz
+pcch: 11
+dphq: 14
+rwvv: wgpl + phfl
+brrs: pfdz * cldw
+vcql: hqpv * stjm
+hqjm: 4
+bhnm: gpjt * wqvz
+dtdn: fcws - ntrh
+hfrf: wvhz / jmwv
+dlhh: 7
+sdfw: flsg * wqbg
+njqm: 3
+lmbs: mpdd + llft
+rlsc: cwzp / pcpc
+bdvw: 2
+lwjf: vthp * btrp
+ffhw: 1
+sbhg: gpqn / mrcm
+bnph: 3
+cwtr: ntjv * fhpf
+lblc: brrs * wjdt
+ppfh: 3
+wfrg: pmms * hdvr
+gvgg: 3
+tffz: lhnl * cfbm
+vcbt: 3
+zvqd: vbft * mjrc
+vdws: 2
+hhmp: 6
+nmlv: 14
+pfdz: 3
+dhwj: 7
+htgv: gltw * wrvb
+vpfr: 2
+cqdn: 3
+jcdg: 2
+szvs: 2
+tppm: zrtm + zbcf
+mwpg: slwd + tfmc
+wvmh: ddjv - dbbn
+mdfs: 5
+vrtr: jdzq + nrfs
+mcwr: lmph * bshl
+jlnf: 4
+hrss: trbp * tlcv
+rtdg: 7
+vlzr: 2
+fccp: wbzf + hptp
+rglz: 13
+slhj: tflm + prjp
+qshz: 2
+tlgs: dbdm * dtdn
+bbls: slln * trcj
+mtjv: 5
+vmzp: hgsq * nvbp
+pfnb: gdng * tmnn
+dntw: vwlv + tqdl
+vpvj: 2
+lbqf: 2
+ghdj: 2
+hgwb: vmjq - phss
+rmbl: 3
+qbsw: fqrh + rwmg
+qzzc: hnzp + cwtr
+gfnw: gzjv * frsc
+vcdl: 2
+pmms: 2
+bfrf: wjfh * zvrg
+tzpw: blwj + nswm
+pqjs: 3
+nwbc: 4
+zvhw: jfnb * znln
+mmtc: ftmb + mwhv
+mmrz: ljnr * gscs
+hmdf: 2
+lshv: mvmf + tlsm
+qlhd: 6
+zvpt: 2
+zjds: 6
+rtbj: fmwm * wvmh
+wtcn: jsvf - jlfq
+grmh: 3
+lbdb: 7
+ftdc: 18
+scch: 5
+hsfc: 12
+lgbn: cnvb * jlzb
+mcbf: 1
+zzdg: 2
+qlpz: qncl + bfwm
+mwcq: 4
+zntt: 8
+djnb: 2
+vghf: 2
+mqjh: dmpn - cgjn
+jclm: dwms * rgjg
+vmwd: gqmc * tdpj
+ptwc: qzqb * rshw
+qtct: fmsm * gsfg
+wrtj: 1
+nttd: bdvw * pgpt
+gvtg: 3
+gltw: jtzh * zwzh
+bbgm: 13
+pmgv: 3
+drbr: 5
+wgsc: 3
+vzjj: fmjd * vrtr
+fcch: 3
+lnpn: 2
+lhpw: 8
+bgff: bccl * jcdg
+zsqz: vqsv + tsvq
+dmrd: shlm + wqfz
+psvh: hnlr - nprj
+rcqf: fcld / dtfc
+mrsm: 5
+gwwr: 4
+hwcr: drmf * zhfp
+zttd: 2
+dlwm: 7
+vqsv: qths * rvnc
+hjvn: 4
+pftp: 7
+wfpf: 2
+dqrz: 3
+rhzd: rltv + cwmd
+bfbd: 13
+mdds: 9
+ztgt: 5
+ftmb: 8
+vtdv: 9
+tjvc: wprn + rmbl
+swnp: vcql - jtwb
+thlj: rpqp + lzng
+ggcf: 9
+mszf: 4
+pplj: nvsm - szss
+tlrc: wvqd + lvwn
+ptcw: qlpz * hwcr
+szqt: zzrb * gpmm
+vvfw: rqgl * lwwl
+tgbv: 2
+jcvp: 5
+vrpq: qwvf * rjdj
+wprn: 8
+zdmc: 13
+pgqs: lwfm / cqgs
+cwzp: dbdl + nvsr
+tvtd: 3
+lqvb: 11
+gsjf: 4
+jrbl: 3
+wgtb: 3
+vbft: 13
+vgmq: jrvm - fqpq
+lhsg: 4
+gsqv: jgrj * dspt
+zsrp: cpmj + lqqp
+sbbm: pqtc + tcrd
+fgtb: 15
+fnnl: 4
+gvvp: zjfl - qdlf
+whlt: 2
+wdlg: 4
+cttl: 4
+fhvf: tmhv + bsgr
+dgjl: 1
+gmnm: 3
+sqsz: 11
+cdms: 2
+tfmc: 3
+tdws: 2
+vsvd: llnh * dzhc
+csjv: smth * gsjl
+nctz: ltsm + wzhg
+ttcf: hcrb * ctlf
+gcln: rhzc + tgcm
+jqhm: 2
+qwhm: thlj * djst
+rchf: pjmc / nnmm
+htzv: 5
+qcdp: 3
+twtl: rqfr * rlnm
+pmjv: 11
+chtc: 3
+rqqc: 3
+crts: 3
+jhjl: 5
+smth: 3
+mjmd: gvft * nnqg
+fqrp: pqnf + jwvq
+dhhp: mvtj * rhwp
+zdrq: 5
+lbvm: jslh + bvqd
+gfnb: 2
+wdbm: 5
+ffdn: 9
+hntj: hfgt * ggrv
+hzpt: 12
+djzw: hsfc + mqqn
+ppmp: 6
+lfbw: 9
+csvf: 2
+jgtw: 5
+qdwz: 3
+tjfb: pvgt + hntz
+dnht: 8
+cfvg: 2
+qzqb: 2
+hrqb: 4
+tbzm: jcvp + ztsb
+hgzw: pjqr + wwbw
+hzrv: 5
+lltl: 2
+hmpv: vlcr / srmz
+tqnb: 4
+llft: jccd * gdfn
+qjpt: 5
+gcwj: 1
+nvbp: 3
+dcpl: cprm * lhpw
+lbdz: 3
+qglg: vffz + fbvb
+jsbf: 13
+nnqg: mwzd / vzws
+qpwj: vzzn - rmwn
+djmw: 4
+cnfh: szqr * ssrr
+qbhs: 3
+rrwh: nlbn - hzdm
+zvsh: dvrs + mmpr
+gbqf: 3
+mssm: bzsr * dqrz
+wbsc: vlzr + mtjv
+qslg: 2
+ccjr: 13
+qvfj: gbtd * fwzh
+zvcm: 13
+mvmf: 1
+glsj: 7
+fmpq: 2
+wzhg: cgrs * pbgg
+wqfz: hzpt + sjct
+hlbn: jznw * drbr
+pbrm: 2
+rcrs: 3
+vdsg: 15
+wgmj: 2
+mrcm: 5
+vgql: 2
+nmgn: 5
+mpnn: 4
+ddhj: gjvc * nmgn
+sjzl: 3
+djmf: vjqj * qjpt
+qbtb: 2
+tmnm: 5
+sfvv: 17
+fbvb: hbvq + ffmg
+jngq: 5
+pttg: psvh * zjjh
+trnb: hzrv * jmls
+dwvg: pplj * gjgg
+gclp: 2
+dqnw: pngt * cttl
+dwsw: stmm * fvmg
+ltcr: 5
+jdqh: plsl + bwqj
+sncw: mwpg * fnnl
+mhlc: ldtb + dwvg
+mvwm: gsvb * pqjs
+nvdh: jbwz * mhzh
+gptn: fzhd + lbdd
+hnlr: shnv + srrm
+zlbl: 2
+lzmq: hcqm * dmrd
+tthb: rbhd / tvqp
+zgjm: 3
+hccl: 2
+ffdl: tdln + mmtc
+bzlq: bhwd * qzfg
+dwgv: 8
+lmch: 2
+wvdj: lgbn + nmjz
+bjcm: tzpw + jljz
+hgsq: 7
+hwrj: lgcg + jlpq
+tmzl: ltgb * hbzl
+cczm: ldrb + cbcc
+hmpw: vrch + jcpc
+tdln: 9
+shnv: whdb * vmzp
+qlsv: 2
+htsg: 4
+szqr: bplb + gtcf
+grcq: czqc / jdsl
+jvbm: zsvt + fgcl
+fllz: ghsl + vjph
+hsbg: zcvp + mwcq
+jdvn: 6
+nsmm: ffhw + rgfr
+mhbr: 8
+nvvj: 19
+htbz: 3
+rlqh: 5
+pttp: 2
+pdmt: pcwb * bfrf
+tdlj: bdzt - jtmc
+bmqt: 16
+gvft: 2
+csqw: 3
+grcp: 1
+rbjt: 3
+rdzz: 11
+rhwp: mmhq / zfpj
+wlbb: mctj * rbjt
+lzng: 6
+gwml: bjsd + cnbs
+pvff: 2
+nprj: 13
+fqrh: qgpz / ppfh
+bwqj: 11
+dmpn: 10
+fvcp: hjvn * rfjj
+bbnf: 3
+bfds: 3
+jzwq: zsrg * szqs
+qlpt: gmbv * dmzn
+mnsw: lmch * nmgq
+qrsc: nbhz - jdln
+mlwj: rzsp * ghdj
+wpfz: gvvp * whgw
+hmmb: 3
+fclp: mtmq + dntw
+fpmt: 5
+sqls: qrsc + rhth
+zgwv: jjpc + hmpw
+fdlh: 19
+wzft: 2
+qqnj: mhbr * hhjc
+qhbl: qflf + pczj
+hfgt: 3
+vggm: nvvj * cwmr
+fhnc: dbjl * fwzb
+rfjj: 4
+rfsw: tmjv + rwwv
+dfqf: lbvm * dmzp
+pfvc: 2
+zmgn: nqlc * jcjn
+gsvb: 5
+nqqf: 13
+snhj: 5
+wmzc: hthb + lbwh
+dwrp: qlhd + wjjb
+cqsd: 16
+cprm: 4
+bgvn: 16
+wbzf: gsqv - pmjv
+ggtm: vsvd + vmwd
+wbbs: mgfm * ftns
+ppjn: 3
+tflm: 11
+gqqg: 4
+jfbn: 5
+shlt: hrlr + phdl
+hzwm: wdbm * wbvr
+zdtq: jcbz + fwgh
+tqrr: gsmd + jmhl
+vfvr: cnfh / jvrt
+vdrt: chzm * dwpw
+npht: vfnf * djnv
+rrhz: 5
+rqfp: mflj + lhrn
+ptbr: 5
+mwnc: mjcq + pdrq
+grnt: 14
+pmqg: wcrn * rrbs
+fvnf: shlt - zlmg
+qgpz: ppjn * wvgz
+llpl: vvcf * gqhf
+clvq: 6
+cglf: plns + grmh
+tzcc: 5
+trbp: crbc * vzdl
+nhbf: qcwb * cfrl
+vpst: jsbf + zdcb
+tvdj: 5
+cwmr: 2
+wcbz: mljm + pmpv
+lfmh: 3
+mzcw: fjqv * mngd
+thfg: lbng - jqzj
+jgrj: wnjr * tvtd
+fjlb: 3
+cwbq: cwbw + rlpd
+vccn: fplg * lfbw
+jjmg: ngpm + hftr
+sjlb: 2
+lgzj: 9
+mqlg: tlgs + lhll
+svsd: ltzc * bmqt
+fprb: 10
+pvgt: fhnc * ghcz
+gnwg: 2
+lrrr: rqfp * qgmg
+hltn: 11
+dqwj: tdlj * nvzv
+cpnw: 5
+rltv: 4
+qqbt: tmlt * mlnv
+vlcr: jhrn * vpvj
+djst: nhzn * lcjr
+dwqn: flgw / zntt
+gpzw: hbmz + qhld
+dcmn: 1
+bnzz: 3
+rsqh: hrpl + zhtm
+fnsh: zjjl + wflc
+jljz: rrjh * vpbm
+sdrs: vrpf / qbdl
+wrvb: 2
+mhzp: 2
+mjcq: jpcf * ndnw
+nnmq: fllz + cdtd
+pbjq: 11
+qgmg: 5
+bwwh: snsh * mgzc
+vrpf: nmzq * jzgm
+jbrm: 4
+gvcw: jmdf * bnnb
+bjcd: 2
+gtzg: 2
+ssmq: lslm + bcph
+brvj: 1
+ftlm: 2
+nvnc: gtrn + npht
+tmjv: 8
+psbh: 9
+cvzc: 2
+nfgf: 8
+cdmp: 3
+hrpl: slhp * sdfw
+rhzc: vggm + mhgr
+gtbr: hwcs * vrhr
+jtls: fcch * hzzt
+jqrz: zmcl * mcwr
+nccd: lfdz + bzdz
+dznv: 3
+ldtm: hmbb + nsmm
+qvdq: 2
+scqw: shgt * grnt
+lzgn: vgql * ttcc
+btrp: hszf + fpdd
+glwz: bdjw * vpwz
+lvmz: lwfz * phhl
+lpwh: 5
+csns: vmdr * swnp
+rqwr: phzl * lsnd
+hndd: wzzh * vntd
+jwfh: ctjd * wbbs
+wmmf: 5
+vwlv: smsj + hhjj
+qtpq: 3
+fjbz: 3
+sttv: gswf + mjhn
+zsrg: hpmc * lbcg
+lqwg: 2
+rpqp: 1
+ggds: 2
+rvrb: hdrn + qpld
+jlfq: 1
+gscs: 2
+hqfg: gwwr + pqfz
+nbjs: hgwb * ppmp
+zsmq: 3
+pgvf: 5
+lmnm: wtcn + dwqn
+ppww: jgrz - sqjg
+tljt: nhbf + zmlb
+nttp: 3
+hrlr: 17
+fwcr: 3
+cszf: mhbg / vghf
+mjmp: 3
+mflj: 1
+rswz: mhzc * rfqf
+sqds: mjmq + mdfs
+cwmd: wcgj + qvbv
+mfsc: tqrr / cjww
+vpwz: 2
+lcps: nmcn * jrwd
+rhgw: vsvp * gdwh
+lwfm: zlbl * bhnm
+jzrj: 3
+qplh: fzzz * tjfb
+lttb: 3
+jrfv: 4
+fhpf: 2
+mmzq: 3
+rpll: cqrh - tdws
+rlzq: mlwj + rgnp
+bffw: rhvf * jfhf
+cslb: 19
+rvnc: 6
+vpjl: gggp * sszs
+stll: cszf * qhbl
+mwjn: qplw + cglf
+cqtl: rcvz * qbhs
+jsvf: smmv + qbsb
+crbc: 3
+chzm: 2
+cjww: 2
+pfsp: chnh * mrdf
+jbhn: 9
+lzbf: 2
+hgsv: crrp * tqnb
+gsmd: pfgm * vhqn
+qbdl: 2
+hqmw: 2
+ndbj: frqg / lbdb
+qttg: fqqp * hsbg
+mctj: flft * hhmp
+ntrh: prcd * mpwt
+flft: 2
+ldrb: 5
+fjfv: swfb * whlt
+rrts: tptp + zfzv
+mhmr: nrtt + wrtj
+sbzj: ppww + wbrz
+wgpl: pvwf + rrhz
+mgcb: 2
+wshg: cjgw * tvch
+prng: rsqh + rswz
+hhwr: 2
+wvqd: 6
+lsgq: qvhs - mrnr
+lvwn: 19
+vmsp: pjrz + sttv
+ljhb: bvwh * gbcj
+vnrz: 5
+jcbz: bfpl * vflc
+cwbr: wvdj * bwhp
+svth: 9
+fjqv: 2
+djnv: 2
+zlmg: 2
+zshr: 2
+whnr: nvnc * djmw
+bcch: 2
+jlbl: 2
+qths: 3
+rrbz: thfg / zcfd
+mhzh: 4
+gdng: mcgv * dhbn
+hhjj: jnqt + qbsw
+zjjl: 2
+prjp: whfl * wtgl
+lhll: rlzq + vjdj
+cpbb: gbqf + prnq
+lfqd: zgwv * drlc
+jbwz: jqgw * dndz
+wftl: 3
+gllj: nwhm + gmhh
+dlrf: 2
+nhvd: tgtv / bdtj
+dbhj: mdsh * scqf
+cplp: 5
+wmph: 3
+csdb: 3
+tvch: 5
+szqs: 15
+qwcv: 11
+dmzn: 5
+vnsj: ggdz * dfpc
+cpjg: tfqr + tthb
+zvjz: lgfc * grpd
+hlrh: 1
+fjls: 11
+dldq: 2
+tsqg: lljn * cvzc
+lpjz: 7
+prmn: 10
+vlch: 6
+rfll: tnhj * ssmq
+zmsb: 2
+gfps: 2
+dbjl: 2
+fpmd: zrtg * rrlr
+svrr: 3
+mpdd: 3
+fnbp: 4
+jcpc: tzwt * mpnn
+dpvd: tffz - rtss
+dspt: 3
+tgrf: zjds * znpj
+gvcj: zmnh + bpjn
+lwvz: 5
+rhgh: 3
+nqlc: 3
+mhvf: 7
+pfvz: wmwm / nflq
+gwsl: 7
+hmbb: vqht + qttg
+lbdd: szvs * pvvz
+jffr: 1
+njdn: 2
+wbvr: 2
+wdrf: cssw + ndtn
+hlth: jwfh - lgzj
+fgcl: tvlv * qlsv
+mlgd: pcch * ggds
+znpj: 5
+pmdv: 15
+mcgv: rbsr + fqrp
+lmtb: csjv + lqwg
+fwpz: lrrr * nttp
+hbmz: bdnm * nftt
+tmnv: 3
+pjdw: 4
+nrzs: pttg + sgml
+cblg: lbgs + ldtm
+ggbt: 18
+flsg: 3
+ffmg: fpmd * gvjs
+bjsd: bbgm * wmzc
+vffz: hqfr * jrpd
+ntjv: 9
+dhzh: vzfq * rwvv
+mwhv: wbht * fjls
+frsc: rcpc + fwpz
+gsfg: jrqb * fwcr
+gfdg: mgln * hlth
+nhzf: 12
+mvlz: ddpq * tvms
+cmdn: 2
+mgbq: 17
+pngt: 3
+szss: 5
+zgjb: 4
+sgpd: zsrp / vpfr
+vzqf: zvjz - grfs
+jtmc: 2
+lbgs: zgjb * wfqq
+vbfg: qglg / vdpc
+dctm: 3
+srmz: 4
+fghr: 3
+stqp: rnbh - qqbt
+mjhn: rdsw + vncz
+jtzh: 17
+mgfm: 2
+gjgg: 3
+bcph: vdws * wqst
+rfgd: nrlz * wwps
+gpmj: 2
+rbsr: slnp + zprg
+htfs: mmrz + dhhp
+sssf: rfgs + rqwr
+tswl: 11
+hwhs: cpnw + fpbv
+jwjr: srmq + jgqz
+gqhf: pjcw + hhwr
+ldtb: rcqf + fljd
+stmf: 17
+rrbs: 7
+cbcc: 2
+qqsq: mngg + rtbj
+jnwq: 4
+qtzl: drhp * ctml
+zcvp: qvnb + jffr
+vmnt: 20
+jvrt: 6
+wznq: tzcc * gssc
+rrlr: qpdz + fjfv
+glbs: trbd + csmf
+qvbv: dsjq * pfvc
+qpld: 7
+zlwh: tmzl / nlbc
+gmhh: 5
+wqbz: cssp * zcpr
+vdpc: 3
+wjrj: nqqf * ttcf
+jccd: 2
+lhnc: 3
+nhbv: fmpq * rrtz
+tbcc: 2
+tsvq: zwct * qncq
+lsnd: 7
+gmsv: cwbq / sjqv
+wjfh: 2
+tcqc: 11
+slln: bfds * mrsm
+cgdf: 9
+wrzn: lzgn * gvgg
+phss: dqnz * mjmd
+rgjg: ggtm + mdps
+lhnl: 2
+bhqt: zgzp * qcdp
+vntd: tvdj * fpnm
+cnvb: 4
+gpww: gwgn * vtdv
+lljn: 13
+mrdt: sgpd * dghz
+jpjr: 7
+brdb: jbtz * scch
+gpvz: hntj + pdtl
+gggp: hfzj / htsg
+thpr: 2
+tqjw: 3
+pnwp: zpqf * vvbg
+bwdn: 6
+lcjr: 2
+plns: lbdz * qjvh
+vqht: qtpq * zvsh
+lbvw: 9
+lbng: ghzp * rlcd
+bpjn: mnsw * fbzj
+bzdz: 14
+qflf: fnbp * mlgd
diff --git a/2022/input/day_21_sample.txt b/2022/input/day_21_sample.txt
new file mode 100644
index 0000000..e14be60
--- /dev/null
+++ b/2022/input/day_21_sample.txt
@@ -0,0 +1,15 @@
+root: pppw + sjmn
+dbpl: 5
+cczh: sllz + lgvd
+zczc: 2
+ptdq: humn - dvpt
+dvpt: 3
+lfqf: 4
+humn: 5
+ljgn: 2
+sjmn: drzm * dbpl
+sllz: 4
+pppw: cczh / lfqf
+lgvd: ljgn * ptdq
+drzm: hmdt - zczc
+hmdt: 32
diff --git a/2022/src/day_21.rs b/2022/src/day_21.rs
new file mode 100644
index 0000000..a82b366
--- /dev/null
+++ b/2022/src/day_21.rs
@@ -0,0 +1,152 @@
+use std::collections::HashMap;
+use std::str::FromStr;
+use Monkey::*;
+use Operation::*;
+
+#[derive(Clone, Copy, Debug)]
+enum Operation {
+    Add,
+    Subtract,
+    Multiply,
+    Divide,
+}
+#[derive(Clone, Debug)]
+enum Monkey {
+    Number(String, i64),
+    Pending(String, String, Operation, String),
+}
+impl FromStr for Monkey {
+    type Err = ();
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let (name, rest) = s.split_once(": ").unwrap();
+        if let Ok(num) = rest.parse::<i64>() {
+            return Ok(Number(name.into(), num));
+        }
+        let (name_left, rest) = rest.split_once(' ').unwrap();
+        let (operation, name_right) = rest.split_once(' ').unwrap();
+        return Ok(Pending(
+            name.into(),
+            name_left.into(),
+            match operation {
+                "+" => Add,
+                "-" => Subtract,
+                "*" => Multiply,
+                "/" => Divide,
+                _ => panic!("expected math symbol"),
+            },
+            name_right.into(),
+        ));
+    }
+}
+
+type Data = HashMap<String, Monkey>;
+type Output = i64;
+fn parse(input: &str) -> Data {
+    input
+        .lines()
+        .map(|s| s.parse::<Monkey>().unwrap())
+        .map(|m| {
+            (
+                match m.clone() {
+                    Number(name, _) => name,
+                    Pending(name, _, _, _) => name,
+                }
+                .to_string(),
+                m,
+            )
+        })
+        .collect()
+}
+fn part_one(mut data: Data) -> Output {
+    fn eval(map: &mut Data, name: &str) -> i64 {
+        let node = map.get(name).unwrap().clone();
+        match node {
+            Number(_, num) => num,
+            Pending(name, left, op, right) => {
+                let left = eval(map, left.as_ref());
+                let right = eval(map, right.as_ref());
+                let res = match op {
+                    Add => left + right,
+                    Subtract => left - right,
+                    Multiply => left * right,
+                    Divide => left / right,
+                };
+                *map.get_mut(&name).unwrap() = Number(name.clone(), res);
+                res
+            }
+        }
+    }
+    eval(&mut data, "root")
+}
+fn part_two(mut data: Data) -> Output {
+    fn eval(map: &mut Data, name: &str) -> Option<i64> {
+        if name == "humn" {
+            return None;
+        }
+        let node = map.get(name).unwrap().clone();
+        match node {
+            Number(_, num) => Some(num),
+            Pending(name, left, op, right) => {
+                let left = eval(map, left.as_ref())?;
+                let right = eval(map, right.as_ref())?;
+                let res = match op {
+                    Add => left + right,
+                    Subtract => left - right,
+                    Multiply => left * right,
+                    Divide => left / right,
+                };
+                *map.get_mut(&name).unwrap() = Number(name.clone(), res);
+                Some(res)
+            }
+        }
+    }
+    fn find_humn(map: &mut Data, name: &str, equals: i64) -> i64 {
+        if name == "humn" {
+            return equals;
+        }
+        let curr = map.get(name).unwrap().clone();
+        match curr {
+            Pending(_, left, op, right) => {
+                if let Some(n) = eval(map, left.as_str()) {
+                    match op {
+                        Add => find_humn(map, right.as_str(), equals - n),
+                        Subtract => find_humn(map, right.as_str(), n - equals),
+                        Multiply => find_humn(map, right.as_str(), equals / n),
+                        Divide => find_humn(map, right.as_str(), n / equals),
+                    }
+                } else {
+                    let n = eval(map, right.as_ref()).unwrap();
+                    match op {
+                        Add => find_humn(map, left.as_str(), equals - n),
+                        Subtract => find_humn(map, left.as_str(), equals + n),
+                        Multiply => find_humn(map, left.as_str(), equals / n),
+                        Divide => find_humn(map, left.as_str(), equals * n),
+                    }
+                }
+            }
+            _ => panic!("expected to do pending"),
+        }
+    }
+    let root = data.get("root").unwrap().clone();
+    match root {
+        Pending(_, left, _, right) => {
+            if let Some(n) = eval(&mut data, left.as_str()) {
+                find_humn(&mut data, right.as_str(), n)
+            } else {
+                let n = eval(&mut data, right.as_str()).unwrap();
+                find_humn(&mut data, left.as_str(), n)
+            }
+        }
+        _ => panic!(),
+    }
+}
+
+advent_of_code_macro::generate_tests!(
+    day 21,
+    parse,
+    part_one,
+    part_two,
+    sample tests [152, 301],
+    star tests [232_974_643_455_000, 3_740_214_169_961]
+);
diff --git a/2022/src/lib.rs b/2022/src/lib.rs
index 78a305e..960b275 100644
--- a/2022/src/lib.rs
+++ b/2022/src/lib.rs
@@ -19,3 +19,4 @@ mod day_17;
 mod day_18;
 mod day_19;
 mod day_20;
+mod day_21;