N = int(raw_input())
K = int(raw_input())
s = range(N)
for loop in xrange(K):
    X,Y = map(int,raw_input().split())
    X -= 1; Y -= 1
    s[X],s[Y] = s[Y],s[X]

a = s[:]
ans = 1
while a != range(N):
    a = [a[i] for i in s]
    ans += 1
print ans