(;
GM[1]
SZ[19]
AW[cf][df][ci][lc][md][mf][pc][pd][qe]
AB[ce][dd][fd][jc][nc][od][oe]
LB[mf:3][oe:2][pd:1]
C[Problem 90. Black to play.  

Continuing from Problem 87, White defends at 1 and jumps to 3. How should Black answer ? ]
(;B[og]
TE[2]
C[Correct Answer.  

Black should simply jump to 1 and, ... ]
;W[qg]
C[... after White defends the right side with 2, ... ]
;B[nh]
C[... play the diagonal move of 3. <= ]
)
(;B[qf]
TE[2]
C[Correct Answer.  

Black could also attach at 1. ]
;W[pe]
C[If White 2, ... ]
;B[of];W[pf];B[og];W[pg];B[oh]
C[... Black and White move down the right side with the moves to 7. White's stones on the left now fall in the shadow of Black's thick wall. <= ]
)
)