(;
GM[1]
SZ[19]
AW[bd][cf][ci][ld][le][me][qf][pj]
AB[cc][dd][fd][jd][ke][lf][nd][pd]
LB[mf:A][me:1]
C[Problem 57. Black to play.  

White seems to be afraid to play 1 at A ( White 5 in the Correct Answer to Problem 55), but White 1 here is a bad move. How does Black take advantage of this mistake ? ]
;B[pf]
TE[2]
C[Correct Answer.  

Black shifts the attack to the right with 1 ... ]
;W[pg];B[of]
C[... and 3. ]
(;W[qe]
LB[pg:2]
C[If White 2 and 4, ... ]
;B[mf]
C[... Black plays 5. The white stones at the top are almost dead. <= ]
)
(;W[mf]
C[Variation.  

If White might turn at 5, ... ]
;B[qg]
C[... Black cuts at 5, seizing the initiative on the right side. <= ]
)
)