(;GM[1]FF[4]SZ[19]
GN[Internal ko threat]
PC[http://senseis.xmp.net/?BeginnerExercise5/Solution]AP[GoWiki:2009]
DT[2009-04-22]
C[Diagram from http://senseis.xmp.net/?BeginnerExercise5/Solution

Internal ko threat]
PL[B]

AB[ra][ob][nc][pc][pd][qd][rd][sd]
AW[pa][sa][pb][qb][rb][qc][rc][sc]
SQ[sa]

;B[sb]C[B1]MN[1]
;W[na]C[W2]MN[2]
;B[oa]C[B3]MN[3]

;SQ[sa]
)
