(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[19]KM[0.00]
PB[Black to play and kill]AW[mq][nq][oq][kr][lr][nr][pr][qr][os]AB[mp][np][op][jq][kq][lq][pq][qq][rq][jr][mr][rr][qs]
(;B[ms]C[Sacrificing two stones should seem natural and is correct.]
(;W[ns]C[White must atari from this side to avoid self-atari.]
;B[rs]C[And black calmly connects here.]
(;W[ps]C[Now for white to make a second eye is self-atari]
;B[or])
(;W[ls]
;B[ps]C[Or if white takes the two stones, black makes the second eye false.]))
(;W[ls]
;B[ks]))
(;B[rs]C[If black connects first]
;W[ms]C[White takes one stone and can make the second eye either side]
(;B[ks]
;W[ps])
(;B[ps]
;W[ks]
;B[or]
;W[pr]))
(;B[ks]C[This move fails too.]
;W[ms]
;B[rs]
;W[ps]
;B[js]
;W[ls]))
