(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]RU[Japanese]SZ[19]KM[0.00]PW[white]PB[black];B[cd];W[pq];B[po];W[pl];B[mp];W[oo];B[on];W[no];B[pp];W[nq](;B[qq];W[oq];B[nn];W[mo];B[qr]LB[jp:A]C[If Black choose to play here, he has to check the ladder, the lasser breaker move and if ther's a white stone at A];W[pn];B[pm];W[qn];B[qm];W[ro](;B[rp];W[rm];B[ql];W[rl];B[qk];W[rk];B[qj];W[ri];B[pr];W[or];B[sr];W[qi]C[now white has two sides and black only a small cornerand black shape is not good for influence because of the single white stone])(;B[qo];W[rn];B[rm];W[rp];B[qp];W[om];B[rk]LB[jp:A]C[If you want to play this shape, you have to double check : ladder and ladder breaker move(and also if ther's or not a white stone at A](;W[nm])(;W[dd];B[dc];W[nm])(;W[qk];B[rl];W[ml];B[mm];W[nm];B[mn](;W[ln]C[turn back to ladder])(;W[lm];B[ln];W[kn];B[lo]LB[jp:A]C[if there's a white stone at A, not good for black !]))))(;B[nn]C[big mistake for black];W[mo];B[qq];W[pr]))