(;AB[pa]AB[pb]AB[qc]AB[rc]AB[sc]AW[sd]AW[rd]AW[qd]AW[pd]AW[oc]AW[ob]AW[oa]C[White to play.]AP[goproblems]
(;W[ra];B[rb]
(;W[pc];B[sa];W[sb]C[White takes the ko first.RIGHT])
(;W[qa];B[sa];W[sb]C[This is a two step ko. White can do better.])
(;W[sa];B[qa]))
(;W[pc];B[ra])
(;W[rb];B[ra]
(;W[sb];B[qb])
(;W[qb];B[sb]))
(;W[qa];B[ra])
(;W[sb];B[ra])
(;W[qb];B[rb]))