# -*- coding: utf-8 -*-


def gcd(a, b):
    while b:
        a, b = b, a % b
    return a

def lcm(a, b):
    return a * b / gcd(a, b)

N = input()
K = input()
Alist = [i+1 for i in range(0, N)]
Blist = [i+1 for i in range(0, N)]
Clist = [0 for i in range(0, N)]
Klist = [0 for i in range(0, K)]
for i in range(0, K):
    Klist[i] = map(int, raw_input().split())[0] - 1
for i in Klist:
        Blist[i], Blist[i+1] = Blist[i+1], Blist[i]
cnt = 0
for i in range(0, N):
    cnt += 1
    for j in range(0, N):
        Alist[j] = Blist[Alist[j]-1]
        if Clist[j] == 0 and Alist[j] == j+1:
            Clist[j] = cnt
cnt = 1
for i in range(0, N):
    cnt = lcm(cnt, Clist[i])
print cnt