(;GM[1]FF[4]SZ[19]
GN[Black to make ko]
PC[https://senseis.xmp.net/?GokyoShumyoSection3Problem87/Solution]AP[GoWiki:2009]
DT[2023-01-21]
C[Diagram from https://senseis.xmp.net/?GokyoShumyoSection3Problem87/Solution

Black to make ko]
PL[B]

AB[bb][gb][cc][ec][fc][cd][dd]
AW[db][hb][bc][gc][ic][bd][ed][fd][gd][ce][cf][ef]
LB[fa:a]

;B[be]C[B1]MN[1]
;W[bf]C[W2]MN[2]
;B[eb]C[B3]MN[3]
;W[cb]C[W4]MN[4]
;B[dc]C[B5]MN[5]
;W[ba]C[W6]MN[6]
;B[ab]C[B7]MN[7]
;W[ca]C[W8]MN[8]
;B[da]C[B9]MN[9]
;W[ea]C[W10]MN[10]

;LB[fa:a]
)
