(;GM[1]FF[4]AP[Drago:4.22.03]SZ[19]CA[UTF-8]AW[rs][rr][rq][qq][pq][qo][qn][pn][on][nn][mn][mo][lq][mp][lr][ls]
[or]AB[ms][mr][mq][np][no][oo][po][pp][pr][qr][oq]C[Black to play and live,]
(;B[nr]C[Incorrect.];W[os])
(;B[os]C[Correct.];W[nr]
(;B[ps];W[qs]
(;B[nq];W[ns]
;B[pr]C[Black plays here to make a second eye under the stones (ishi-no-shita).];W[ps];B[os])
(;B[ns]C[This is self-atari.]))
(;B[ns]C[Mistake.];W[ps];B[nq]
;W[or]C[Snap-back shape.])))
