EVENT
BOARDSIZE 19
SETUP W D16 C10 E9 F10 F8 F7 C8 C6 D6 D4 E3 M10 L9 L8 K8 J7 J6 H6 J4 O17 Q18 R17 
SETUP B F3 F4 E8 E7 E6 F6 G6 G7 H7 H8 J8 J10 K9 L10 L11 N4 Q3 Q9 Q16 Q14 M17 M15 
MARK \t@J4 \t@J6 \t@H6 \t@J7 \t@K8 \t@L8 \t@L9 \t@M10
COM
Problem 78. Black to play.  

How should Black attack the marked white stones ? 
ENDCOM
B 1 L6
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

Black should peep at 1 to destroy White's eye shape.
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  VAR
  B 1 M9
  COM
  Failure.

  Cutting with 1 ...
  ENDCOM
  W 2 L6
  COM
  ... lets White make an eye with 2.
  ENDCOM
  B 3 N9
  W 4 R5
  COM
  Since her stones are now relatively secure, she can invade Black's
  sphere of influence in the lower right with 4.
  <=
  ENDCOM
  ENDVAR
W 2 L7
B 3 N6
W 4 N8
B 5 M11
W 6 N10
B 7 O9
COM
After Black 7, White's stones have barely one eye, while Black
is threatening to make a moyo in the lower right.
<=
ENDCOM