EVENT
BOARDSIZE 19
SETUP W L17 O17 O16 R5 R4 Q3 P4 D3 D5 
SETUP B D16 C10 J17 P17 Q16 Q14 Q10 Q5 Q6 R6 
MARK A@L15 C@K3 B@C8
COM
Problem 120. White to play.  

White has many good points to play, but there is one which takes
precedence over all the others. Which of the three points indicated
is best ? 
ENDCOM
W 1 L15
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

White should strengthen her group by jumping to 1 and aim at
invading the upper right and left corners.
ENDCOM
  VAR
  W 1 K3
  COM
  Failure.

  White 1 is also a good point, but ...
  ENDCOM
  B 2 K15
  COM
  ... Black 2 is a severe attack. White must escape, but then Black's
  moyo on both the left and the right will be strengthened.
  <=
  ENDCOM
  ENDVAR
B 2 J15
COM
If Black 2, ...
ENDCOM
W 3 C17
MARK 2@J15 A@D14
COM
... White 3 is the perfect invasion. Black could also play 2
at A.
<=
ENDCOM