(;AP[goproblems]AB[cp]AB[dp]AB[eq]AB[fp]AB[gp]AB[go]AB[gn]AB[fn]AB[en]AB[eo]AB[dn]AB[cn]AB[bn]AW[bl]AW[cl]AW[dl]AW[fm]AW[gm]AW[hn]AW[ho]AW[hp]AW[gq]AW[fq]AW[er]AW[dr]AW[cq]AW[bp]AW[bo]AW[co]C[5. Black lives](;B[bq](;W[br](;B[dq](;W[cr]C[CHOICE](;B[do]LB[bq:1]LB[br:2]LB[dq:3]LB[cr:4]LB[do:5]C[Cutting at 1 is a beautiful, tempo-gaining sacrifice. White has to reply at 2, and Black lives with 3 and 5. RIGHT])(;B[ao];W[ap]C[](;B[do]C[RIGHT])(;B[an];W[aq];B[do]C[RIGHT]))(;B[ap];W[ao]C[];B[do]C[RIGHT]))(;W[do];B[cr];W[aq];B[cq];W[cs];B[ep](;W[an](;B[am];W[ap];B[ao]C[RIGHT])(;B[ap]C[RIGHT]))(;W[ap](;B[ar];W[as];B[ao];W[an];B[am](;W[ar];B[ao];W[ds];B[bs]C[RIGHT])(;W[ds];B[ao];W[bs];B[ar]C[RIGHT])(;W[bm];B[ao]C[RIGHT]))(;B[an];W[ar];B[bs];W[as];B[ao]C[RIGHT]))))(;B[aq](;W[dq]C[CHOICE];B[ao];W[ar])(;W[ap]C[](;B[do];W[ar];B[dq]C[])(;B[dq]C[]))(;W[ao];B[dq];W[cr];B[do]C[])))(;W[dq](;B[br]LB[bq:1]LB[dq:2]LB[br:3]C[If White tries to resist with 2, Black extends at 3 and captures three stones. RIGHT])(;B[aq]C[];W[br](;B[ao];W[ar])(;B[ar];W[ap])(;B[do];W[ar])(;B[ap];W[ao]))))(;B[dq];W[do]C[CHOICE])(;B[do];W[dq])(;B[ao];W[dq])(;B[br];W[bq](;B[dq];W[do])(;B[do];W[dq])))