(;AB[nb]AB[oc]AB[mc]AB[pc]AB[qc]AB[qd]AB[rd]AW[sc]AW[rc]AW[qb]AW[pb]AW[ob]C[Black to play. How can Black kill the white stones?]SZ[19]CA[utf-8]FF[4]ST[2]RU[Japanese]AP[CGoban:3]GM[1]PB[Musta]PW[Valkea]KM[0]MULTIGOGM[1]
(;B[ra];W[rb]
(;B[sa];W[oa];B[qa]C[RIGHT]C[Bent-four-in-the-corner.RIGHT])
(;B[qa];W[sa];B[sb];W[pa])
(;B[oa];W[sa];B[sb];W[qa]))
(;B[oa];W[ra]
(;B[pa];W[sb])
(;B[sa];W[sb])
(;B[sb];W[pa])
(;B[qa];W[pa]))
(;B[rb];W[ra];B[oa];W[sb])
(;B[sd];W[ra];B[oa];W[pa];B[sb];W[rb])
(;B[sb];W[ra];B[sd];W[rb];B[oa];W[pa])
(;B[qa];W[ra];B[sb];W[rb])
(;B[sa];W[ra];B[oa];W[pa]))