It's another problem I made. Feel free to comment.
(;AP[goproblems]AW[ap]AW[bp]AW[ar]AW[br]AW[dq]AB[cp]AB[dp]AB[ep]AB[fq]AB[fr]AB[fs]AB[bo]AB[cn]C[Black to kill White's corner.](;B[cr](;W[cq];B[dr](;W[bs];B[bq]C[CHOICERIGHT])(;W[bq];B[bs])(;W[cs];B[er](;W[bs];B[bq])(;W[bq];B[bs])))(;W[dr](;B[cq]C[CHOICERIGHT])(;B[cs];W[cq](;B[ds];W[bs];B[es];W[bq])(;B[bs];W[ds])(;B[bq];W[ds]))(;B[bq];W[cq])(;B[bs];W[cq];B[ds];W[cs]C[You can do better than ko.])))(;B[cq];W[bq](;B[bs];W[cr];B[cs];W[ds])(;B[cr];W[bs])(;B[dr];W[cr]))(;B[bq];W[cq](;B[cr];W[dr])(;B[dr];W[cr])(;B[cs];W[cr](;B[ds];W[bs])(;B[bs];W[ds]))(;B[ds];W[cs]))(;B[bs];W[cr](;B[cs];W[ds])(;B[bq];W[cq];B[cs];W[ds])(;B[cq];W[bq];B[cs];W[ds]))(;B[cs];W[cr](;B[bs];W[ds])(;B[cq];W[bq](;B[dr];W[bs])(;B[bs];W[ds])))(;B[dr];W[cr];B[cq];W[bq]))