(;AB[sb]AB[rc]AB[qc]AB[pc]AB[oc]AB[re]AW[rb]AW[qb]AW[rf]AW[qf]AW[pe]AW[nc]AW[nd]AW[nb]AW[oa]C[Black to force a ko.]AP[goproblems]
(;B[pa];W[pb];B[ob];W[qa];B[ra];W[sa]C[RIGHT])
(;B[ob];W[pa])
(;B[pb];W[pa];B[qa];W[ra];B[sa];W[qa])
(;B[qa];W[pb];B[ob];W[pa];B[ra];W[na])
(;B[ra];W[pb];B[ob];W[pa])
(;B[sa];W[pb];B[ob];W[pa])
(;B[na];W[ob]
(;B[ma];W[lb])
(;B[pb];W[pa];B[qa];W[ra];B[sa];W[qa])))