(;AB[rb]AB[rc]AB[qc]AB[pc]AB[od]AB[nd]AB[ne]AB[mf]AB[lf]AB[kf]AB[je]AB[jd]AB[jc]AB[jb]AB[kc]AB[of]AW[kb]AW[lc]AW[kd]AW[ke]AW[le]AW[me]AW[md]AW[nc]AW[oc]AW[pb]AW[qb]AW[ra]C[Black to attack the white stones and get the best result!]AP[goproblems]
(;B[nb]
(;W[mb];B[ob];W[mc];B[pa];W[la]C[Well done! Black captures three white stones in sente!CHOICERIGHT])
(;W[lb];B[ob])
(;W[ob];B[mb]TR[lb]TR[mc]))
(;B[mb];W[mc]
(;B[lb];W[nb]C[Black captures one stone in sente, but there is a better result.])
(;B[nb];W[lb];B[ob];W[oa]TR[sa]C[Black can't approach the white stones, so white kills the three black stones.]MA[mb]MA[nb]MA[ob]))
(;B[lb];W[mb];B[ka]C[Black captures one stone in gote. No good =(]))