(;GM[1]FF[4]SZ[19]
GN[one move approach ko]
PC[https://senseis.xmp.net/?GokyoShumyoSection4Problem18/Solution]AP[GoWiki:2009]
DT[2022-12-29]
C[Diagram from https://senseis.xmp.net/?GokyoShumyoSection4Problem18/Solution

one move approach ko]
PL[B]

AB[bc][ec][fc][gc][cd][ce][ee][df]
AW[eb][cc][dc][bd][be][cf][cg]

;B[bb]C[B1]MN[1]
;W[cb]C[W2]MN[2]
;B[ba]C[B3]MN[3]
;W[ca]C[W4]MN[4]
;B[da]C[B5]MN[5]
;W[fb]C[W6]MN[6]
;B[gb]C[B7]MN[7]
;W[ga]C[W8]MN[8]
;B[ha]C[B9]MN[9]
;W[ea]C[W10]MN[10]

;
)
