(;AB[as]AB[bs]AB[dr]AB[ds]AB[es]AB[er]AB[aq]AB[bq]AB[cq]AB[ap]AB[bp]AB[bo]AB[dp]AB[ep]AB[eo]AW[dq]AW[eq]AW[fq]AW[fr]AW[fs]AW[fp]AW[fo]AW[fn]AW[dn]AW[en]AW[cn]AW[co]AW[bn]AW[an]AW[ao]C[How should white play here?]AP[goproblems]
(;W[cr]
(;B[br]
(;W[cs];B[dr]
(;W[cp];B[ds]C[RIGHT])
(;W[er];B[ds];W[cp]C[White loses sente.])
(;W[ds];B[es]
(;W[er];B[ds])
(;W[ds];B[cs])))
(;W[cp];B[cs]C[Not optimal.]))
(;B[cs];W[br]C[RIGHT])
(;B[cp];W[cs]C[RIGHT]))
(;W[cp];B[cr]C[Not optimal.])
(;W[cs];B[cr])
(;W[br];B[cr]))