(;AB[bh]AB[bi]AB[ch]AB[di]AB[dj]AB[ck]AB[cl]AB[cm]AB[bm]AB[bn]AW[bo]AW[co]AW[cn]AW[dm]AW[dl]AW[bg]AW[cg]AW[ek]AW[ej]AW[ei]AW[dh]AW[dg]AW[ag]AW[ci]AW[bj]LB[bj:1]C[White plays 1. Black to prevent white from killing him.]AP[goproblems] (;B[aj] (;W[ai] (;B[cj];W[ak] (;B[al];W[ah] (;B[bk];W[ci] (;B[an]C[RIGHT]) (;B[aj]C[RIGHT])) (;B[an];W[bk];B[bl];W[ci]) (;B[ci];W[aj] (;B[bk];W[an]) (;B[an];W[bk]))) (;B[bk];W[al];B[aj]C[This is a ko whereas black can live unconditionally.])) (;B[bk];W[ah] (;B[al];W[an]) (;B[an];W[al]))) (;W[ak] (;B[cj];W[ai] (;B[al];W[ah] (;B[bk];W[ci] (;B[an]C[RIGHT]) (;B[aj]C[RIGHT])) (;B[an];W[bk];B[bl];W[aj])) (;B[bk];W[al];B[aj]C[This is a ko whereas black can live unconditionally.])) (;B[bk];W[ai] (;B[al];W[an] (;B[cj];W[aj];B[ah]C[RIGHT]) (;B[aj];W[ah])) (;B[an];W[al];B[cj];W[aj])))) (;B[bk];W[ai] (;B[al];W[an] (;B[aj];W[ah]) (;B[cj];W[aj];B[ah];W[ci])) (;B[cj];W[aj] (;B[ak];W[ah] (;B[al];W[an]) (;B[an];W[al])) (;B[ah];W[ci])) (;B[aj];W[ah] (;B[al];W[an]) (;B[an];W[al]))) (;B[ah];W[ai]) (;B[ai];W[cj];B[dk];W[aj]) (;B[ak];W[ai];B[cj];W[aj];B[bk];W[ah]TR[al]TR[an] (;B[al];W[an]) (;B[an];W[al])) (;B[cj] (;W[aj] (;B[ah];W[ai];B[ci]C[RIGHT]) (;B[ai];W[ah];B[ci];W[bk] (;B[bl];W[ak] (;B[an];W[al]) (;B[al];W[an])) (;B[ak];W[al];B[bl];W[ak];B[am];W[ak]) (;B[al];W[an])) (;B[bk];W[ai];B[ak];W[ah]TR[al]TR[an] (;B[al];W[an]) (;B[an];W[al]))) (;W[ai]C[CHOICE] (;B[bk];W[aj] (;B[ah];W[ci]) (;B[ak];W[ah]TR[al]TR[an] (;B[al];W[an]) (;B[an];W[al]))) (;B[ak];W[aj] (;B[ah];W[ci]) (;B[bk];W[ah]TR[al]TR[an] (;B[al];W[an]) (;B[an];W[al]))) (;B[ah];W[ci]) (;B[al];W[aj]TR[an]TR[bk]) (;B[an];W[aj]TR[al]TR[bk]) (;B[aj] (;W[bk];B[bl];W[ak];B[al]C[RIGHT]) (;W[ak]C[CHOICE] (;B[bk];W[al];B[aj]C[This is a ko whereas black can live unconditionally.]) (;B[al] (;W[ah]C[CHOICE] (;B[an];W[bk];B[bl];W[aj]) (;B[bk];W[ci] (;B[aj]C[RIGHT]) (;B[an]C[RIGHT]))) (;W[bk];B[bl]C[RIGHT]) (;W[an];B[bk] (;W[ah];B[aj]C[RIGHT]) (;W[aj];B[ah]C[RIGHT]))) (;B[ah];W[ci]) (;B[an];W[al])))) (;W[ah];B[aj]C[RIGHT])))