(;
GM[1]
SZ[19]
AW[ce][dd][fd][ic][lc][qf][qi]
AB[nc][ne][qd][cf][df][di]
C[Problem 118. White to play.  

Black's position at the top is vulnerable. Where should White invade ? ]
;W[qc]
TE[2]
C[Correct Answer.  

White 1 is the vital point. ]
(;B[pd]
C[If Black 2, ... ]
;W[rd];B[re];W[rc];B[qe];W[ob]
C[... White lives with the moves to 7. <= ]
)
(;B[pc]
C[Variation.  

If Black blocks with 2, ... ]
;W[rc];B[rd];W[pb]
LB[pd:A][rc:3]
C[... White will play 3 and 5. Since White has the cutting point of A, she can live. <= ]
)
)