(;GM[1]FF[4]SZ[19]
GN[Blocking]
PC[http://senseis.xmp.net/?GokyoShumyoSection1Problem71/Solution]AP[GoWiki:2009]
DT[2009-04-22]
C[Diagram from http://senseis.xmp.net/?GokyoShumyoSection1Problem71/Solution

Blocking]
PL[B]

AB[qb][oc][pc][od][qd][rd][qe]
AW[mb][ob][nc][pd][me][pe][re][nf][pf][qf][rf]

;B[pb]C[B1]MN[1]
;W[rc]C[W2]MN[2]
;B[rb]C[B3]MN[3]
;W[sd]C[W4]MN[4]

;
)
