EVENT
BOARDSIZE 19
SETUP W D16 K16 O17 D4 O3 R3 
SETUP B Q16 Q14 Q10 Q4 C10 M3 
MARK 1@O3 2@M3 3@R3 \t@Q10
COM
Problem 2. Black to play.  

Black has made a sanren-sei with the marked stone. Against White
1, the pincer of Black 2 is often played. How does Black answer
White 3 ? 
ENDCOM
B 1 R4
MARK \t@Q10
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

With the marked stone in the middle of the right side in place,
Black 1 is the only move.
ENDCOM
  VAR
  B 1 Q3
  MARK \t@Q10
  COM
  Failure.

  With the marked black stone in place, Black 1 is the wrong direction.
  ENDCOM
  W 2 R4
  B 3 Q5
  W 4 Q2
  B 5 P2
  W 6 R2
  B 7 P3
  W 8 R6
  MARK \t@Q10
  COM
  After White 8, the marked stone is misplaced and is not working
  efficiently.
  <=
  ENDCOM
  ENDVAR
W 2 Q3
B 3 P4
W 4 O2
B 5 N5
COM
The sequence to Black 5 is a joseki which is often seen in sanren-sei
fusekis.
<=
ENDCOM