(;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]AP[goproblems]
(;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]))