(;GM[1]FF[4]AP[Drago:4.22.03]SZ[19]CA[UTF-8]AB[rq][sp][qp][ro][qo][po][op][oo][nq][mq][lq][mr]AW[rr][sr][qq][pq][pp][oq][nr][np]C[Black to kill]
(;B[or]C[If White plays here Black just gives up one stone to live.];W[pr];B[ns];W[ps])
(;B[qr]C[Sometimes this kind of cut works.];W[pr];B[qs];W[os];B[sq]
;W[ps]C[White makes two eyes.])
(;B[ns];W[ps];B[or]
;W[pr]C[Again White gives up a stone to live,])
(;B[ps]C[This is the correct play.]
(;W[or]C[If White connects here...]
(;B[os]C[This play is essential.];W[ns]
;B[qr]C[... then this play makes White short of liberties.])
(;B[qr]C[Black should not play here immediately.];W[pr]
;B[rs]C[This is a ko.];W[qs]))
(;W[qs];B[or])
(;W[pr];B[ns];W[qs];B[os])))
