import numpy as np

int1 = lambda x: int(x) - 1

N = int(input())
K = int(input())
F = np.arange(N)
A = np.arange(N)
for _ in range(K):
    x, y = map(int1, input().split())
    F[x], F[y] = F[y], F[x]
F_tmp = F.copy()

ans = 1
while (F_tmp != A).any():
    F_tmp = F_tmp[F]
    ans += 1
print(ans)