(;GM[1]FF[4]SZ[19]
GN[Internal attack]
PC[http://senseis.xmp.net/?BeginnerExercise118/Solution]AP[GoWiki:2009]
DT[2009-04-22]
C[Diagram from http://senseis.xmp.net/?BeginnerExercise118/Solution

Internal attack]
PL[B]

AB[on][pn][qn][rn][mo][oo][ro][np][sp][nq][sq][or][rr][ps][qs]
AW[ol][pl][ql][nm][rm][mn][sn][lo][po][qo][lp][op][qp][rp][mq][oq][pq][rq][mr][pr][qr]

;B[nr]C[B1]MN[1]
;W[ss]C[W2]MN[2]
;B[ns]C[B3]MN[3]
;W[rs]C[W4]MN[4]
;B[sr]C[B5]MN[5]

;
)
