(;AB[as]AB[bs]AB[cs]AB[cr]AB[dr]AW[er]AW[fs]AW[fr]AW[es]AW[cq]AW[dq]AW[ar]AW[aq]AB[gs]AB[gr]AB[gq]AB[fq]AB[ep]AB[do]AB[co]AB[bo]AP[goproblems]
(;B[br];W[bq];B[eq];W[ds]
(;B[bs]
(;W[cs];B[cr]C[RIGHT])
(;W[br]
(;B[cr]C[RIGHT])
(;B[cs];W[cr];B[dr];W[er];B[es];W[ds];B[fs]C[RIGHT]))
(;W[cr];B[cs];W[br];B[dr];W[er];B[es];W[ds];B[fs]C[RIGHT]))
(;B[cs];W[bs];B[dr];W[cr])
(;B[cr];W[bs]))
(;B[bq];W[bp];B[eq];W[br];B[ds];W[er])
(;B[eq];W[br]
(;B[ds];W[er])
(;B[bq];W[bp];B[ds];W[er])
(;B[ap];W[ds]))
(;B[bp];W[bq];B[eq];W[br]
(;B[ds];W[er])
(;B[ap];W[ds]
(;B[cr];W[cs])
(;B[cs];W[cr];B[dr];W[er];B[es];W[ds]C[It is ko, but the problem stated black had no ko threats, so white can live.])))
(;B[ap];W[bq]
(;B[ds];W[eq])
(;B[eq];W[br];B[ds];W[er]))
(;B[ds];W[br];B[cs];W[bs]))