(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[19]KM[0.00]
PB[Black to play]AW[nn][on][pn][lo][mo][qo][lp][qp][lq][qq][lr][or][qr][ms][ns][ps]AB[qm][qn][ro][kp][rp][kq][rq][kr][mr][rr][ks][ls][qs][rs]C[Does White need to defend?]
(;B[nr]C[This atari could be dangerous.]
;W[os]
(;B[oq]
;W[pr]
;B[po]C[But this is not atari.]
;W[pp]C[So White is alright.])
(;B[pr]C[If Black tries the throw-in here.]
;W[oq]C[White can simply extend and is fine.]))
(;B[pr]C[Hoever can start with the throw-in, so White should have defended.]
(;W[pq]
;B[nr]C[At this point White should give up two edge stones.]
(;W[os]
;B[oq]
;W[pr]
;B[po]C[White runs out of liberties.]
;W[pp]
;B[op])
(;W[nq]
;B[os]
;W[ns]C[White loses points but saves must of the group.]))
(;W[oq]C[White's best defence is this.]
;B[os]C[White can either fight the ko..]
;W[nr]C[... or just connect.])
(;W[os]C[This connection doesn't work either for White.]
;B[oq]
;W[pq]
;B[nr]
;W[pr]
;B[po])))
