(;AW[br]AW[bq]AW[bp]AW[bo]AW[ao]AB[cr]AB[cq]AB[cp]AB[co]AB[do]AW[an]AW[bn]AW[bm]AW[am]AW[bl]AW[al]AW[bk]AW[ak]AB[cn]AB[dn]AB[dm]AB[cm]AB[cl]AB[dl]AB[dk]AB[ck]TR[es]TR[eq]TR[er]TR[ep]TR[eo]TR[en]TR[em]TR[el]TR[ek]TR[ej]TR[dj]TR[cj]TR[bj]TR[aj]C[A simple problem. Black can kill white. Enjoy!FORCE]AP[goproblems]
(;B[as]TR[es]TR[er]TR[eq]TR[ep]TR[eo]TR[en]TR[em]TR[el]TR[ek]TR[ej]TR[dj]TR[cj]TR[bj]TR[aj]LB[bs:a]C[What's this first move?FORCE];W[bs]TR[es]TR[er]TR[eq]TR[ep]TR[eo]TR[en]TR[em]TR[el]TR[ek]TR[ej]TR[dj]TR[cj]TR[bj]TR[aj]LB[cs:a]C[Black can be alive but...FORCE];B[cs]TR[es]TR[er]TR[eq]TR[ep]TR[eo]TR[en]TR[em]TR[el]TR[ek]TR[ej]TR[dj]TR[cj]TR[bj]TR[aj]C[White wins by 1 point.])
(;B[bs]TR[es]TR[er]TR[eq]TR[ep]TR[eo]TR[en]TR[em]TR[el]TR[ek]TR[ej]TR[dj]TR[cj]TR[bj]TR[aj]LB[cs:a]C[This first move is very good. What does black have to do if white plays more?FORCE];W[cs]TR[es]TR[er]TR[eq]TR[ep]TR[en]TR[eo]TR[em]TR[el]TR[ek]TR[ej]TR[dj]TR[cj]TR[bj]TR[aj]LB[ar:a]LB[ds:b]C[Which is better a or b?FORCE]
(;B[ar]TR[es]TR[er]TR[eq]TR[ep]TR[eo]TR[en]TR[em]TR[el]TR[ek]TR[ej]TR[dj]TR[cj]TR[bj]TR[aj]LB[as:a]C[Black missed the atari.FORCE];W[as]TR[es]TR[er]TR[eq]TR[ep]TR[eo]TR[en]TR[em]TR[el]TR[ek]TR[ej]TR[dj]TR[cj]TR[bj]TR[aj]C[Black has no ko threat.])
(;B[ds]TR[es]TR[er]TR[eq]TR[ep]TR[eo]TR[en]TR[em]TR[el]TR[ek]TR[ej]TR[dj]TR[cj]TR[bj]TR[aj]LB[dq:a]C[Can white kill black?FORCE];W[dq]TR[es]TR[er]TR[eq]TR[ep]TR[eo]TR[en]TR[em]TR[el]TR[ek]TR[ej]TR[dj]TR[cj]TR[bj]TR[aj]LB[ar:a]C[Black is not dead beacause he can crash all the points of white by the last move.FORCE];B[ar]TR[es]TR[er]TR[eq]TR[ep]TR[eo]TR[en]TR[em]TR[el]TR[ek]TR[ej]TR[dj]TR[cj]TR[bj]TR[aj]C[If white plays on A3, it will be self killing.RIGHT]))
(;B[cs]TR[es]TR[er]TR[eq]TR[ep]TR[eo]TR[en]TR[em]TR[el]TR[ek]TR[ej]TR[dj]TR[cj]TR[bj]TR[aj]LB[bs:a]C[Black is alive but...FORCE];W[bs]TR[es]TR[er]TR[eq]TR[ep]TR[eo]TR[en]TR[em]TR[el]TR[ek]TR[ej]TR[dj]TR[cj]TR[bj]TR[aj]C[Tie is not the best.])
(;B[ds]TR[es]TR[er]TR[eq]TR[ep]TR[eo]TR[en]TR[em]TR[el]TR[ek]TR[ej]TR[dj]TR[cj]TR[bj]TR[aj]LB[bs:a]C[What's this first move?FORCE];W[bs]TR[es]TR[er]TR[eq]TR[ep]TR[eo]TR[en]TR[em]TR[el]TR[ek]TR[ej]TR[dj]TR[cj]TR[bj]TR[aj]LB[cs:a]LB[dq:b]C[White could create his points. And what happenes if black plays on a or b?FORCE]
(;B[cs]TR[es]TR[er]TR[eq]TR[ep]TR[eo]TR[en]TR[em]TR[el]TR[ek]TR[ej]TR[dj]TR[cj]TR[bj]TR[aj]LB[dq:a]C[White can't let black be alive.FORCE];W[dq]TR[es]TR[er]TR[eq]TR[ep]TR[eo]TR[en]TR[em]TR[el]TR[ek]TR[ej]TR[dj]TR[cj]TR[aj]TR[bj]C[The worst result.])
(;B[dq]TR[es]TR[er]TR[eq]TR[ep]TR[eo]TR[en]TR[em]TR[el]TR[ek]TR[ej]TR[dj]TR[cj]TR[bj]TR[aj]LB[cs:a]C[White can't let black be alive.FORCE];W[cs]TR[es]TR[er]TR[eq]TR[ep]TR[eo]TR[en]TR[em]TR[el]TR[ek]TR[ej]TR[dj]TR[cj]TR[bj]TR[aj]C[The worst result.])))