(;GM[1]FF[4]CA[UTF-8]AP[CGoban:2]ST[2] RU[Japanese]SZ[19]KM[0.00] ;AW[ao][bo][co][cp][dp][ep][rp][fq][gq][hq][hr][mr][nr][or][pr][hs]AB[qo][ro][so][bp][op][pp][qp][bq][lq][mq][nq][dr][er][fr][gr][lr][ls]LB[rq:B][cr:A]C[If you think the left black group need another stone to live play at A. If you think the left black group is alredy alive play at B. ]PL[B] (;B[rq] ;W[cq] (;B[cr] ;W[br] (;B[ar] ;W[bs] (;B[aq] ;W[ap] (;B[cs] ;W[as] ;B[bq]C[RIGHT]) (;B[gs] ;W[cs] ;B[ds] ;W[as] ;B[bq] ;W[aq] ;B[ar] ;W[bs] ;B[br]C[RIGHT])) (;B[cs] ;W[aq]C[Black dies.]) (;B[gs] ;W[aq]C[Black dies.])) (;B[bs] ;W[ar]C[Black dies.]) (;B[cs] ;W[aq]C[Black dies.]) (;B[gs] ;W[aq]C[Black dies.])) (;B[bs] ;W[cr]C[Black dies.]) (;B[br]CR[br] ;W[cr]CR[cr] ;B[cs]CR[cs] ;W[gs]CR[gs]C[Black has only one eye in the corner, and none at the edge.])) (;B[cr] ;W[rq]C[Now the problem is for Black to kill the White right group.] (;B[qq] ;W[qr] (;B[rr] ;W[sr] (;B[rs] ;W[sq] (;B[sp] ;W[qs] ;B[ss]CR[ss] ;W[rq]CR[rq]C[White lives.]) (;B[qs] ;W[ps]C[White lives.]) (;B[ms] ;W[ns] (;B[qs] ;W[ps]C[White lives.]) (;B[sp] ;W[qs] ;B[ss]CR[ss] ;W[rq]CR[rq]C[White lives.]))) (;B[sq] ;W[rs]C[White lives.])) (;B[sp] ;W[sr]C[White lives.]) (;B[sq] ;W[sr]C[White lives.]) (;B[sr] ;W[rr]C[White lives.]) (;B[rs] ;W[rr]C[White lives.]) (;B[ms] ;W[sr]C[White lives.])) (;B[sp] ;W[qr]C[White lives.]) (;B[sq] ;W[rr]C[White lives.]) (;B[sr] ;W[rr]C[White lives.]) (;B[rr] ;W[qq]C[White lives.]) (;B[rs] ;W[rr]C[White lives.]) (;B[qr] ;W[qq]C[White lives.]) (;B[qs] ;W[qr]C[White lives.])))