(;AB[hs]AB[gr]AB[fr]AB[es]AB[bs]AB[ir]AB[jr]AB[hq]AB[hp]AB[gp]AB[go]AB[gn]AB[fn]AB[em]AB[dm]AB[cn]AB[cp]AB[dp]AB[dq]AB[bp]AB[bq]AB[io]AB[ko]AB[kp]AB[kq]AB[lp]AB[mp]AB[mq]AW[ks]AW[kr]AW[lr]AW[lq]AW[mr]AW[nr]AW[jq]AW[jp]AW[ip]AW[jo]AW[jn]AW[ho]AW[hn]AW[hm]AW[gm]AW[fm]AW[en]AW[eo]AW[fo]AW[fq]AW[eq]AW[er]AW[dr]AW[ds]AW[cr]AW[br]AW[ar]AW[cq]AB[mn]AW[oq]C[white to kill]AP[goproblems] (;W[js] (;B[fs] (;W[is];B[gq];W[iq];B[dn]C[Black makes a three-step ko for the corner. White can do better.]) (;W[iq];B[gq];W[is];B[dn]C[Black makes a three-step ko for the corner. White can do better.]) (;W[gq];B[is];W[iq]C[RIGHT])) (;B[iq] (;W[fs]C[RIGHT]) (;W[is];B[fs];W[gq]C[RIGHT]) (;W[gq];B[is];W[fs]C[RIGHT])) (;B[gq] (;W[fs]C[RIGHT]) (;W[is];B[fs];W[iq];B[dn]C[Black makes a three-step ko for the corner. White can do better.]) (;W[iq];B[fs];W[is]C[];B[dn]C[Black makes a three-step ko for the corner. White can do better ])) (;B[is] (;W[fs]C[RIGHT]) (;W[gq];B[fs];W[iq]C[RIGHT]) (;W[iq];B[fs];W[gq]C[RIGHT]))) (;W[iq];B[js];W[fs];B[gq]) (;W[gq];B[js] (;W[fs];B[iq]) (;W[iq];B[fs])) (;W[fs]C[];B[js] (;W[gq];B[iq]) (;W[iq];B[gq])))