(;AW[rb]AW[sc]AW[rd]AB[rc]AB[qc]AB[qb]AB[pb]AB[ob]AB[oc]AW[qd]AW[pd]AW[od]AW[pc]AW[re]AB[qe]AB[qf]AB[qg]AB[rf]AB[mc]AW[ne]C[Show white`s error about his extension move...basic one !]AW[ra]MA[ra]AW[nf]AW[mg]AW[lh]AW[mf]AB[qh]AB[nc]AP[goproblems] (;B[qa];W[sb]C[:-( ... lost a couple of points buddy !]) (;B[sb];W[sa];B[qa]LB[sb:A]LB[sd:B]C[Yes...Now white can choose between either A losing five stones , or B losing three stonesRIGHT]) (;B[sd];W[sb]C[:-(]) (;B[sa];W[sb]C[Black lost his chance]) (;B[se];W[sd]C[:-(]))