EVENT
BOARDSIZE 19
SETUP W D17 C15 C12 K17 N17 
SETUP B C10 R17 R14 P17 H17 
MARK 1@H17 \t@P17
COM
Reference Diagram to Problem 157.

If Black had the marked stone in place, then an invasion at 1might
be playable, since it attacks the two white stones on the right.
<= 
ENDCOM