(;GM[1]FF[4]SZ[19]
GN[The result is a ko.]
PC[https://senseis.xmp.net/?HitachiNumber7/Solution]AP[GoWiki:2009]
DT[2020-06-11]
C[Diagram from https://senseis.xmp.net/?HitachiNumber7/Solution

The result is a ko.]
PL[B]

AB[gb][bc][fc][gc][bd][cd][dd][ed][be]
AW[fa][bb][fb][ac][cc][dc][ec]

;B[ba]C[B1]MN[1]
;W[cb]C[W2]MN[2]
;B[ab]C[B3]MN[3]

;
)
