(;AB[se]AB[re]AB[qe]AB[qd]AB[pd]AB[pc]AW[pb]AW[qb]AB[ob]AW[oc]AB[nc]AW[od]AW[oe]AW[pe]AW[pf]AW[qf]AW[rf]AW[sf]AB[na]C[Black to live. There are no ko threats elsewhere on the board.]AB[nb]AP[goproblems]
(;B[rc];W[rb]
(;B[sb]
(;W[sd]
(;B[sc]
(;W[qc];B[rd];W[ra];B[pa]C[RIGHT])
(;W[ra]
(;B[pa];W[qc];B[rd]C[RIGHT])
(;B[qc];W[sa]
(;B[pa];W[rd])
(;B[qa];W[rd]))
(;B[sa];W[qc];B[rd];W[sd])))
(;B[rd]
(;W[sa]
(;B[ra];W[qa]
(;B[sc];W[sa];B[pa]C[RIGHT];W[oa];B[ra]C[RIGHT])
(;B[pa];W[sa];B[sc]C[RIGHT];W[oa];B[ra]C[RIGHT]))
(;B[sc]C[RIGHT]))
(;W[ra];B[pa];W[sa];B[sc]C[RIGHT])))
(;W[sc];B[sd];W[sa];B[ra];W[qa];B[pa];W[sa];B[sc];W[oa];B[ra]C[RIGHT])
(;W[sa];B[ra];W[qa];B[sc];W[sa];B[pa];W[oa];B[ra]C[RIGHT]))
(;B[sc];W[sb]
(;B[sd];W[qc])
(;B[qc];W[sd]))
(;B[sd];W[sb];B[sc];W[qc])
(;B[sa];W[sb];B[sc]
(;W[sd];B[rd];W[qc])
(;W[qc];B[rd];W[sd]))
(;B[pa];W[sc];B[sd];W[sb];B[qa];W[qc];B[ra];W[rd]))
(;B[rb];W[rc]
(;B[sc];W[qc];B[sd];W[ra];B[sb])
(;B[sb];W[sc]
(;B[qc];W[ra];B[rd];W[sd])
(;B[rd];W[qc])))
(;B[sc];W[rc]
(;B[rd];W[sb])
(;B[sb];W[rd];B[sd];W[rb];B[pa];W[qc]))
(;B[sb];W[rc]
(;B[ra];W[sd]
(;B[rd];W[qc])
(;B[sc];W[rd]))
(;B[qc];W[sd]))
(;B[ra];W[rc];B[sc];W[sb];B[rb];W[sd]))