(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2] SZ[13] AW[ca][ja][ab][bb][cb][jb][mb][cc][jc][ad][bd][jd][kd][ae][ke][af][if][ag][jg][kg][ah][ii][ki][li]AB[da][db][kb][lb][bc][dc][kc][dd][ld][be][ce][de][bf][bg][bh][ai][bi]LB[cd:A]C[Make life for the 4 stones in the upper right corner! You have one ko threat at A (C10). Assume there are no further ko threats on the rest of the board!]PL[B] (;B[ka] ;W[mc] (;B[ma] ;W[le] (;B[md] ;W[la] ;B[cd] ;W[ac] ;B[ma]C[Correct! :) RIGHT]) (;B[lc] ;W[la] ;B[cd] ;W[ac] ;B[ma]C[Correct! :) RIGHT])) (;B[md] ;W[ma]) (;B[lc] ;W[ma] ;B[le] ;W[lf]) (;B[le] ;W[lc])) (;B[mc] ;W[la] (;B[ma] ;W[ka] ;B[le] ;W[mb] ;B[cd] ;W[ac] ;B[ma] ;W[lf] ;B[me] ;W[mb]) (;B[le] ;W[ka] ;B[ma] ;W[me] ;B[lf] ;W[mb] ;B[cd] ;W[ac] ;B[ma] ;W[mf] ;B[lg] ;W[mb])) (;B[le] ;W[la] ;B[mc] ;W[ka] ;B[ma] ;W[me] ;B[lf] ;W[mb] ;B[cd] ;W[ac] ;B[ma] ;W[mf] ;B[lg] ;W[mb]))