(;GM[1]FF[4]SZ[19]
GN[a above]
PC[https://senseis.xmp.net/?IgoHatsuyoRonProblem145/Solution]AP[GoWiki:2009]
DT[2023-02-03]
C[Diagram from https://senseis.xmp.net/?IgoHatsuyoRonProblem145/Solution

a above]
PL[W]

AB[pa][ib][kb][ob][qb][ic][kc][lc][mc][qc][id][jd][nd][qd][le][ne][pe][qf]
AW[ja][ka][jb][lb][mb][nb][pb][jc][pc][kd][od][pd][ke][oe][jf][mf][nf][kg][og]

;W[oc]C[W1]MN[1]
;B[na]C[B2]MN[2]
;W[la]C[W3]MN[3]
;B[nc]C[B4]MN[4]

;
)
