EVENT
BOARDSIZE 19
SETUP W C14 H17 H15 O17 O15 R12 L15 
SETUP B D16 F16 F14 Q16 Q14 L17 P13 
MARK \t@L17 3@L15 2@P13 1@O15
COM
Reference Diagram to Problem 50.

In this situation, if Black invaded deeply with the marked stone,
Black has no effective moves to rescue this stone after White
3.
<=
ENDCOM