(;GM[1]FF[4]SZ[19]
GN[Ko]
PC[http://senseis.xmp.net/?BeginnerExercise154/Solution]AP[GoWiki:2009]
DT[2009-05-07]
C[Diagram from http://senseis.xmp.net/?BeginnerExercise154/Solution

Ko]
PL[W]

AB[an][bn][bo][co][cp][dp][ep][eq][ar][er][fr][fs]
AW[ao][ap][bp][cq][br][dr][ds][es]
LB[as:a]

;W[bq]C[W1]MN[1]
;B[bs]C[B2]MN[2]
;W[cs]C[W3]MN[3]
;B[dq]C[B4]MN[4]

;LB[as:a]
)
