N = int(input())
k = int(input())
K = tuple([tuple(map(int, input().split(' '))) for i in range(k)])
count = 0
l = [i for i in range(1, N + 1)]
i = 0
while True:
    x, y = K[i]
    l[x - 1], l[y - 1] = l[y - 1], l[x - 1]
    i += 1
    if i == k:
        count += 1
        i = 0
    for j, n in enumerate(l):
        if j + 1 != n:
            break
    else:
        break

print(count)