(;GM[1]FF[4]SZ[19]
GN[White opts for ko]
PC[http://senseis.xmp.net/?BeginnerExercise170/Solution]AP[GoWiki:2009]
DT[2009-04-22]
C[Diagram from http://senseis.xmp.net/?BeginnerExercise170/Solution

White opts for ko]
PL[B]

AB[ma][oa][mb][nb][ob][pb][pc][pd][pe][mf][nf][pf][mg][lh][mh][li][ni][lj][mj][nj]
AW[la][qa][lb][qb][lc][mc][qc][ld][qd][le][me][ne][qe][lf][of][qf][kg][lg][ng][pg][qg][kh][oh][ki][oi][kj][oj][kk][lk][mk][nk]

;B[oe]C[B1]MN[1]
;W[nc]C[W2]MN[2]
;B[og]C[B3]MN[3]

;
)
