(;GM[1]FF[4]SZ[19]
GN[Two stage ko.]
PC[http://senseis.xmp.net/?BeginnerExercise140/Solution]AP[GoWiki:2009]
DT[2009-04-22]
C[Diagram from http://senseis.xmp.net/?BeginnerExercise140/Solution

Two stage ko.]
PL[B]

AB[cb][db][bc][dc][dd][ce][de][bf][df]
AW[bb][cc][bd][cd][be][cf][cg][ch]
LB[bg:a]

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

;LB[bg:a]
)
