What is wrong with my code?

IARCS:

• Runtime Error: EXIT
• Description: Program did not return 0

 
def main():
	Nths = []
	N = int(input())
	for x in range(N):
		Nths.append(list(map(int, input().split())))
 
	p1 = 0
	p2 = 0
	# max: [which player (1/2), MAX_difference]
	max = [0,0]
 
	# core
	for nth in Nths: