def gcd(a,b):
    if(b==0):
        return a
    else:
        return gcd(b,a%b)
 
n = int(input())
p = [0] + [int(x) for x in input().split()]
vis = [0 for i in range(n+1)]
 
ans = 1
 
for i in range(1,n+1):
    if(vis[i] == 0):
        u = p[i]
        l = 1
        vis[i] = 1
        while(vis[u] == 0):
            l+=1
            vis[u] = 1
            u = p[u]
        ans = ans*l//gcd(ans,l)
 
ans = str(ans)
if len(ans) > n:
    ans = ans[-n:-1]
print(ans)