A convex polygon has N vertices. Every interior angle is smaller than 180∘, and the vertices are numbered 1 through N in clockwise order.
Seonggwan and Hongjun play a game on this polygon. Seonggwan moves first, and the two players alternate turns.
On a turn the player picks two vertices and draws the segment that joins them. The segment is allowed to lie on a side of the polygon. The new segment must not meet any segment drawn earlier. Two segments that touch at an endpoint count as meeting.
The player who cannot draw a segment loses. Given N, write a program that decides who wins when both players play optimally.