(;AB[ap]AB[bp]AB[bq]AB[cq]AB[dr]AW[ao]AW[bo]AW[co]AW[cp]AW[dp]AW[dq]AW[er]AW[es]AW[fq]AW[ep]C[Black to live.]AP[goproblems]
(;B[ar];W[cr]
(;B[br];W[ds];B[bs]C[RIGHT])
(;B[bs];W[ds]
(;B[br]C[RIGHT])
(;B[cs];W[dr];B[br]C[RIGHT]))
(;B[cs];W[ds];B[bs];W[dr];B[br]C[RIGHT]))
(;B[br];W[ds]
(;B[ar];W[bs])
(;B[bs];W[ar])
(;B[cs];W[ar];B[as];W[bs]C[White kills with double ko.])
(;B[cr];W[cs]))
(;B[cr];W[ar]
(;B[br];W[bs])
(;B[bs];W[ds])
(;B[ds];W[bs]C[Bent-four.]))
(;B[bs];W[ar]
(;B[br];W[ds])
(;B[cr];W[ds])
(;B[ds];W[cr]))
(;B[cs];W[ar];B[br];W[ds];B[as];W[bs]C[White kills with double ko.]))