(;
GM[1]
SZ[19]
AW[kc][ld][od][pc][qc]
AB[dc][ce][ic][mc][rc][qd][re][pf]
LB[ld:2][mc:1]
C[Problem 40. Black to play.  

White responds Black's invasion with the diagonal move of 2. How should Black respond ? ]
;B[md]
TE[2]
C[Correct Answer.  

Black should push up with 1, ... ]
;W[me];B[kb]
C[... then attach with 3. ]
;W[jb];B[lb];W[jc]
C[After White 6, ... ]
;B[ib];W[ne];B[ja]
LB[ib:7]
C[... Black links up his stones with 7 and 9, ... ]
;W[je]
LB[ne:8]
C[... while White makes thickness in the center with 8 and 10. <= ]
)
)