(;AB[qc]AB[ob]AB[nb]AB[lb]AB[mc]AB[lc]AW[kb]AW[kc]AW[jd]AW[ld]AW[md]AW[nd]AW[oc]AB[pc]AW[nc]AW[pd]AW[qd]AB[rd]AB[rc]AW[re]AW[qf]AW[ka]C[And the best endgame is... sente matters...]AP[goproblems] (;W[ma];B[mb] (;W[la];B[ja]C[And if black tenukis now? (classic shape)] (;W[pb];B[qb] (;W[na];B[ra] (;W[sb];B[pa]) (;W[oa];B[sb]C[You could kill the whole corner])) (;W[ra];B[pa] (;W[na]C[Black is dead, very good endgame! :o)RIGHT]) (;W[sd];B[na])) (;W[oa];B[pa];W[na];B[ra]C[You could do better]) (;W[sb];B[pa];W[ra];B[na]C[Black is alive with points])) (;W[pa];B[pb]) (;W[qa];B[pa];W[qb];B[rb] (;W[na];B[sd]) (;W[sd];B[sc];W[ra];B[na];W[sb];B[se])) (;W[qb];B[pb];W[rb];B[sb];W[ra];B[pa];W[na];B[sd]C[Black is ok])) (;W[pb];B[qb];W[la];B[ja]C[And if black tenukis now?] (;W[na];B[ra] (;W[sb];B[pa]) (;W[oa];B[sb]C[You could kill the whole corner])) (;W[ra];B[pa] (;W[na]C[Black is dead, very good endgame! :o)RIGHT]) (;W[sd];B[na])) (;W[oa];B[pa];W[na];B[ra]C[You could do better]) (;W[sb];B[pa];W[ra];B[na]C[Black is alive with points]))) (;W[mb];B[ma];W[la];B[mb]C[Black keeps a lot]) (;W[la];B[mb] (;W[ma];B[ja]C[And if black tenukis now? (classic shape)] (;W[pb];B[qb] (;W[na];B[ra] (;W[sb];B[pa]) (;W[oa];B[sb]C[You could kill the whole corner])) (;W[ra];B[pa] (;W[na]C[Black is dead, very good endgame! :o)RIGHT]) (;W[sd];B[na])) (;W[oa];B[pa];W[na];B[ra]C[You could do better]) (;W[sb];B[pa];W[ra];B[na]C[Black is alive with points])) (;W[pa];B[pb]) (;W[qa];B[pa];W[qb];B[rb] (;W[na];B[sd]) (;W[sd];B[sc];W[ra];B[na];W[sb];B[se])) (;W[qb];B[pb];W[rb];B[sb];W[ra];B[pa];W[na];B[sd]C[Black is ok])) (;W[na];B[pb]C[Black protects and the marked white stone is not placed optimally - it would be better at n19]TR[na])) (;W[na];B[mb];W[la]C[];B[pb]C[Black protects and the marked white stone is not placed optimally - it would be better at n19]TR[na]))