(;
GM[1]
SZ[19]
AW[fc][cm][dm][em][fm][fn][bn][bo][cp][cq][dq][dr][po][pp][pq][oq][or][lq][oc][pe][id][jc]
AB[dd][cf][dj][ck][co][cn][dn][dp][ep][eo][en][fq][bp][bq][br][cr][qr][pr][qq][qp][qn][nq][kd][kc]
LB[kc:A][jc:B][kd:C]
C[Problem 87. White to play.  

After Black invades at A, White attaches with B, How should White play after Black stands with C ?  

[You will find a supplement to this Problem Diagram as "Problem 142"] ]
;W[jf]
TE[2]
C[Correct Answer.  

Black's two stones at the top are heavy, so White 1 is the perfect attacking point. ]
;B[kf]
C[If Black attaches with 2, ... ]
;W[kg]
C[... White drives Black's stones toward her position in the upper right with 3 ... ]
;B[lf];W[lg]
C[... and 5. ]
;B[mf];W[nh];B[of];W[pf];B[og];W[oi];B[pg];W[qi];B[qg];W[re];B[oe];W[od]
C[White defends with 17, and Black's stones are in trouble. Next ... ]
;B[jg]
C[... Black cuts with 18, ... ]
;W[if];B[jh]
C[... then extends to 20 to get some aji on the outside ... ]
;W[ki];B[md]
C[... before securing his stones with 22. ]
;W[ji]
C[White switches to the center ... ]
;B[hg];W[ii];B[hh];W[fe]
C[... and attacks black's stones with the sequence to 27. ]
;B[ec];W[fb];B[fg]
C[After Black 30, ... ]
;W[om]
C[... White maps out a moyo in the center with 31. <= ]
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