(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[19]KM[0.00]
PB[Black to play]
AB[rs][rr][rq][qp][pp][op][nq][mq][lr][ls][mo]
AW[qs][qr][qq][pq][oq][nr][mr][lq][kq][jr]C[This is the problem position. Black to play.]
(;B[ms]C[If black tries simple moves to capture white...]
;W[or]C[.. white just connects]
;B[ns]
;W[ks]
;B[os]
;W[kr]C[And black runs out of liberties.])
(;B[ns]C[Again if black plays here]
;W[or]C[...white connects and wins]
;B[ms]
;W[ks]
;B[os]
;W[kr])
(;B[or]C[So adding a stone to stop the white connection must be the trick.]
(;W[ms]C[This is self atari])
(;W[ns]
;B[os]C[This clearly fails])
(;W[os]C[This must be the strongest white answer]
(;B[ns]C[Black can play here]
(;W[pr]
;B[ms]C[And now white is short of liberties]
;W[or]
;B[ps])
(;W[ms]
;B[ns]C[This clearly fails]))
(;B[ms]
;W[pr]
;B[ns]C[This ends up at the same shape.]))))
