(;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[qo][ro][pp][rp][pq][or][pr][rr][os]AB[on][qn][rn][po][op][qp][mq][oq][qq][rq][nr]
(;B[sp]C[This captures three stones, but White can live at the bottom.]
;W[qr]
;B[so]
;W[sr])
(;B[sq]C[This looks good.]
(;W[qr]C[If White plays here Black kills.]
(;B[sp]
;W[sr])
(;B[sr]
;W[qs]))
(;W[sr]C[So White must play here.]
(;B[qr]
;W[qs])
(;B[qs]
;W[qr])))
(;B[sr]C[This is the correct move.]
;W[qr]
;B[sq]
;W[rs]C[White can only make one eye.]
;B[so]))
