def printans(cupball):
	for i in range(0, 3):
		if cupball[i]:
			return i+1
	return -1

n = int(raw_input())
m = int(raw_input())
cupball = [False, False, False]
cupball[n-1] = True
for i in range(0, m):
	inpt = map(int, raw_input().split())
	tmp = cupball[inpt[0]-1]
	cupball[inpt[0]-1] = cupball[inpt[1]-1]
	cupball[inpt[1]-1] = tmp

print printans(cupball)