(;GM[1]FF[4]SZ[19]
GN[Official solution]
PC[https://senseis.xmp.net/?HitachiNumber121]AP[GoWiki:2009]
DT[2021-02-19]
C[Diagram from https://senseis.xmp.net/?HitachiNumber121

Official solution]
PL[B]

AB[bb][cb][gb][bc][cc][ec][gc][dd][ed][gd][ce][cf][bg][cg]
AW[ba][ca][db][eb][fb][dc][bd][cd][be][bf]

;B[da]C[B1]MN[1]
;W[ea]C[W2]MN[2]
;B[ab]C[B3]MN[3]

;
)
