(;GM[1]FF[4]AP[Drago:4.22.03]SZ[19]CA[UTF-8]AW[sq][rr][rp][qp][ps][or][oq][np][oo][po][nn][nm][mo][lo]AB[sp][so][ro][qo][pp][pn][pm][ol][nl][ml][lm][kn][ko][kp][lp][mp]
[nq][nr][ns][os][lr][rm]C[Black to play and kill]
(;B[qq]C[This looks promising but does not work.];W[rq]
(;B[pr]
(;W[qr];B[qs];W[pq])
(;W[qs]C[However this is better as Black has no useful play left because of shortage of liberties.];B[rs]C[This doesn't help Black.];W[ss]))
(;B[pq];W[qr]))
(;B[pq]C[This does not work either.];W[pr];B[qq];W[rq])
(;B[pr]C[This is the correct first play, but the second is not obvious.];W[qs]
(;B[pq]C[This fails.];W[op])
(;B[rs]C[This is the key play.]
(;W[qr]
(;B[pq]C[This is wrong.];W[op])
(;B[qq]C[This is correct - if White connects it is self-atari.]
(;W[rq];B[sr])
(;W[pq]
;B[rq]C[White is dead.])))
(;W[ss]C[This is White's strongest reply];B[qr]
(;W[rs]C[This is wrong.];B[qq])
(;W[pq]C[This is White's best continuation.];B[rs]
(;W[qs]C[This is again wrong.];B[qq]
;W[op]C[Only one eye in the corner.])
(;W[qq]C[This is White's best chance leading to an unfavourable Ko for the group.];B[sr]))
(;W[qq]C[6 and 8 can be played in either order.];B[rs];W[pq];B[sr])))))
