(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[19]KM[0.00]
PW[White]PB[Black to play and kill]AW[lo][mo][no][oo][lp][pp][lq][nq][oq][pq][lr][pr][ls][qs]AB[km][mm][om][ln][pn][ko][po][kp][mp][np][op][qp][kq][mq][qq][kr][mr][qr][ks][ms][rs]C[Black has only two liberties to White's three, so filling a liberty 
will not work..]
(;B[on]C[Filling a liberty on this white string fails.]
;W[nr]
;B[mn]
;W[ns])
(;B[nr]C[This fails.]
;W[or]
;B[os]
;W[ns])
(;B[ps]C[Taking this stone to fill a liberty doe not work either.]
;W[nr]
;B[ns]
;W[os])
(;B[or]C[This takes a liberty too but also fails.]
;W[nr]
;B[ns]
;W[os])
(;B[ns]C[This does not help]
;W[os]
;B[ps]
;W[nr])
(;B[os]C[This is the correct move, a tesuji that takes aim at White's bad shape.]
(;W[ps]
;B[or]
;W[nr]
;B[ns])
(;W[or]
;B[ps]
;W[nr]
;B[ns])
(;W[nr]
;B[ns]
;W[ps]
;B[or])
(;W[ns]
;B[nr]
(;W[or]
;B[ps])
(;W[ps]
;B[or]))))
