(;GM[1]FF[4]SZ[19]
GN[]
PC[http://senseis.xmp.net/?BeginnerExercise143/Solution]AP[GoWiki:2009]
DT[2009-04-22]
C[Diagram from http://senseis.xmp.net/?BeginnerExercise143/Solution

]
PL[W]

AB[nm][kn][pn][rn][no][jp][kp][np][lq][nq][pq][qq][pr][rr][sr][qs]
AW[in][ip][op][pp][qp][rp][iq][jq][oq][rq][or]
LB[qm:a][rs:b]

;W[ns]C[W1]MN[1]
;B[kr]C[B2]MN[2]
;W[ps]C[W3]MN[3]
;B[os]C[B4]MN[4]

;LB[qm:a][rs:b]
)
