(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[19]KM[0.00]
PB[Black to play and live]AW[on][pn][qn][mo][ro][mp][rp][lq][nq][rq][sq][nr][qr][sr][qs]AB[po][qo][np][op][qp][mq][pq][qq][mr][rr][rs]
(;B[pr]C[Black needs to capture one of the pairs of white stones to live.

However if Black starts with the atari on the corner two white stones then Black gets neither pair.]
;W[ss]
;B[ns]
;W[lr]
;B[ms]
;W[os])
(;B[or]C[This move does not work either.]
;W[lr]
;B[ps]
;W[ss])
(;B[ns]C[This is the correct move as it leaves Black's options open.]
;W[lr]
;B[ms]
;W[os]C[Black sacrifices four stones. ]
;B[ps]C[Now this double atari is the good move.]
;W[pr]
;B[or]C[This double atari is a snap-back if captured, so Black captures something for sure.]
(;W[ls]
;B[ps]
(;W[oq]C[This threatens to make the top eye false.]
;B[ns]C[After this Black can make two eyes in two ways so is safe.]
(;W[oo]
;B[qr])
(;W[qr]
;B[oo]))
(;W[ns]
;B[pr]))
(;W[ss]
;B[oq])))
