(;AW[cr]AW[dq]AW[eq]AW[fq]AW[gr]AW[gs]AB[cq]AB[cp]AB[bp]AB[dp]AB[ep]AB[fp]AB[gp]AB[gq]AB[hr]AB[iq]AB[co]C[black to make ko]AP[goproblems]
(;B[cs]
(;W[br]
(;B[es];W[er]C[CHOICE]
(;B[dr]C[ko is the best black can get hereRIGHT])
(;B[fr];W[fs])
(;B[hs];W[fr];B[dr]C[RIGHT])
(;B[ds];W[bs])
(;B[ar];W[bs])
(;B[bs];W[fs]))
(;B[hs];W[es])
(;B[ds];W[es])
(;B[ar];W[ds]
(;B[er];W[dr])
(;B[bs];W[er])
(;B[es];W[bs]))
(;B[bs];W[ds])
(;B[dr];W[es]))
(;W[ds];B[br]
(;W[bs];B[er]C[RIGHT])
(;W[er];B[dr]C[RIGHT])))
(;B[br];W[cs]
(;B[er];W[es])
(;B[es];W[er])
(;B[bs];W[es])
(;B[hs];W[es]))
(;B[es];W[er]
(;B[cs];W[fs])
(;B[hs];W[ds])
(;B[br];W[ds])
(;B[ds]
(;W[dr]C[thanks to hubz for finding mistake hereCHOICE]
(;B[hs];W[cs];B[fs];W[fr];B[es];W[br];B[ar];W[aq])
(;B[br];W[fs])
(;B[fs];W[br]))))
(;B[er];W[dr]
(;B[br];W[es])
(;B[es];W[br])
(;B[fr];W[es])
(;B[hs];W[es]))
(;B[bs];W[cs])
(;B[ds];W[es]
(;B[er];W[dr];B[fs];W[fr];B[es];W[br])
(;B[br];W[cs])
(;B[cs];W[dr])
(;B[dr];W[er])))