#include<bits/stdc++.h>

#define ll long long
#define pii pair<int,int>
#define pll pair<ll,ll>
#define fi first
#define se second
#define sz size
#define pb push_back
#define mp make_pair
#define bg begin
#define nd end
using namespace std;

#define maxn 100003

int a[maxn];
int viz[maxn];
vector<int> divs;
int n;

int dfs(int x) {
	if (viz[x]) return 0;
	viz[x] = 1;
	return 1+dfs(a[x]);
}

void print_divs() {
	for(int i=0;i<divs.size();++i) {
		cerr << divs[i] << '\n';
	}
}

int main() {

	freopen("perm2.in", "r", stdin);
	freopen("perm2.out", "w", stdout);

	ios_base::sync_with_stdio(false);
	cin.tie(0);

	cin >> n;
	for (int i = 1; i <= n; ++i) {
		cin >> a[i];
	}
	for (int i = 1; i <= n; ++i) {
		if (!viz[i]) divs.pb(dfs(i));
	}

	int ans = divs[0];
	for (int i = 1; i < divs.size(); ++i) {
		int GCD = __gcd(ans, divs[i]);
		ans = (ans * divs[i]) / GCD;
	}
	cout << ans << '\n';

	return 0;
}