EVENT
BOARDSIZE 19
SETUP W D16 E17 D14 D4 K3 K16 K13 
SETUP B Q3 Q5 Q16 N16 F17 F16 G13 
MARK A@Q10
COM
Supplement to Problem 45: Black's mistake.

Instead of extending to A, ...
ENDCOM
B 1 H16
USER
CORRECT ANSWER
ENDUSER
COM
... Black should have played 1. It is now White who has to make
shape for her stones.
ENDCOM
W 2 M15
COM
White 2 ...
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B 3 N15
W 4 M14
COM
... and 4 are the usual way to do so, but ...
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B 5 O13
MARK 3@N15
COM
... these moves provoke 3 and 5, enabling Black to begin building
a moyo in the upper right.
<=
ENDCOM