(;GM[1]FF[4]SZ[19]
GN[Difficult ko]
PC[https://senseis.xmp.net/?KyuExercise173/Solution]AP[GoWiki:2009]
DT[2022-12-14]
C[Diagram from https://senseis.xmp.net/?KyuExercise173/Solution

Difficult ko]
PL[B]

AB[ao][bo][co][do][ep][eq][er][es]
AW[bp][cp][cr][dr][ds]

;B[br]C[B1]MN[1]
;W[bq]C[W2]MN[2]
;B[as]C[B3]MN[3]
;W[dq]C[W4]MN[4]
;B[aq]C[B5]MN[5]
;W[ap]C[W6]MN[6]
;B[dp]C[B7]MN[7]

;
)
