(;AB[ra]AB[rb]AB[rc]AB[qd]AB[pd]AB[nd]AB[od]AB[me]AB[le]AB[kd]AB[kc]AB[kb]AW[lb]AW[lc]AW[ld]AW[nc]AW[oc]AW[pc]AW[qb]AW[qa]AB[ib]C[]AP[goproblems]
(;B[pb]
(;W[mb]C[See variations why white has to answer here]
(;B[qc];W[ob]
(;B[pa];W[md];B[oa];W[na]C[CHOICERIGHT])
(;B[oa];W[na];B[pa];W[md]C[CHOICERIGHT]))
(;B[ob];W[qc]
(;B[la];W[md]
(;B[ma];W[na]
(;B[ka];W[nb])
(;B[nb];W[ka]))
(;B[na];W[nb];B[ma];W[oa]))
(;B[md];W[oa]
(;B[na];W[nb];B[pa];W[oa])
(;B[mc];W[nb];B[la];W[ma])
(;B[nb];W[mc];B[la];W[ma]C[You can't kill, so you are better off capturing the two stones.])
(;B[la];W[ma]
(;B[mc];W[nb])
(;B[nb];W[mc])))
(;B[nb];W[oa]
(;B[md];W[mc];B[la];W[ma])
(;B[la];W[ma];B[md];W[mc])))
(;B[la];W[ob]))
(;W[ob];B[mb];W[mc];B[la];W[nb];B[ma];W[na];B[pa]C[RIGHT])
(;W[pa];B[la];W[mb];B[ob]C[RIGHT])
(;W[oa];B[qc];W[pa];B[mb]C[Black to reduce white as much as possible]))
(;B[mb];W[mc]
(;B[la];W[ma];B[na];W[oa]
(;B[ka];W[nb];B[ma];W[pb])
(;B[ma];W[nb];B[ka];W[pb]C[Not good enough])
(;B[pb];W[nb];B[qc];W[ma];B[pa];W[ob]LB[ka:a]LB[ja:b]C[As later White can exchange a for b in sente, this is 2/3 points worse than the correct answer.]))
(;B[pb];W[pa];B[la];W[nb];B[ma];W[na];B[ka];W[ob]))
(;B[la];W[mb]
(;B[pb];W[ob])
(;B[md];W[ob]))
(;B[na];W[nb]
(;B[la];W[oa];B[ma];W[mb];B[ka];W[md])
(;B[oa];W[ma])
(;B[ma];W[la])))