(;
GM[1]
SZ[19]
AW[jd][nc][ql][qn][dm][ck][cj][ch][rp]
AB[pj][dj][dp][pd][pp][dd][gc][pf][qj][jp][gp][fj][dk][nq]
TR[rp]
C[Problem 90. Black to play.  

White has just played the marked stone (White 2 in the game in Problem 86). What should Black do next ? ]
(;B[lc]
TE[2]
C[Correct Answer.  

All of Black's stones are strong, but White's two stones at the top are still weak. Now is the time to attack them by invading at 1. ]
;W[ld];B[kd]
LB[ld:2]
C[Since the ladder is favourable for Black, he will answer White 2 by wedging in with 3. ]
;W[kc];B[ke];W[lb];B[jc];W[kb];B[id];W[le];B[je]
(;W[pb];B[lf]
C[Up to 13, a black moyo in the center has begun to emerge. <= ]
)
(;W[lg]
C[If White 12 here, ... ]
;B[oc]
C[... Black will attach at 13. <= ]
))
(;B[qq]
C[How the game continued.  

Black defended with 1. The territory he got was big, but ... ]
;W[hn]
LB[hp:A]
C[... White got the chance to go on the offensive with 2, aiming to start a fight by attaching at A. If Black defended, White would go after the three stones in the middle. The game was now more difficult that if Black had played the moves in the Correct Answer. <= ]
)
)