(;GM[1]FF[4]SZ[19]
GN[Black to play: a or b?]
PC[http://senseis.xmp.net/?DontHelpYourOpponentExercise3]AP[GoWiki:2009]
DT[2010-01-22]
C[Diagram from http://senseis.xmp.net/?DontHelpYourOpponentExercise3

Black to play: a or b?]
PL[W]

AB[nc][pd][qd][qe][re][qi]
AW[qc][rc][rd][qf][qk][qm]
LB[lc:a][md:b]

;W[ob]C[W1]MN[1]
;B[nb]C[B2]MN[2]
;W[oc]C[W3]MN[3]
;B[od]C[B4]MN[4]
;W[nd]C[W5]MN[5]

;LB[lc:a][md:b]
)
