EVENT
BOARDSIZE 19
SETUP W F17 F16 K17 R16 S16 S15 
SETUP B E17 D16 D14 N17 R17 Q16 Q15 R15 R10 
MARK 1@R17
COM
Problem 139. White to play.  

How does White respond to Black 1 ? 
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W 1 S17
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

White first forces with 1, ...
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  VAR
  W 1 R13
  COM
  Failure.

  Jumping to 1 first allows Black ...
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  B 2 S17
  MARK A@S14
  COM
  ... to block with 2 in sente, he now threatens to play A. This
  is a setback for White.
  <=
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  ENDVAR
B 2 R18
W 3 R13
COM
... then jumps lightly to 3.
<=
ENDCOM