#include <bits/stdc++.h>
using namespace std;
int n;
int d[200];
int h[200];
int eler[200];
bool kor[200];
long long ko[200];
int kv;
int dfs(int ke, int r) {
  if (eler[ke]) return -1;
  eler[ke] = r;
  if (eler[h[ke]] == r) {
    kor[ke] = 1;
    if (h[ke] == ke) return -1;
    d[ke] = 1;
    return h[ke];
  }
  int ret = dfs(h[ke], r);
  d[ke] = d[h[ke]] + 1;
  if (ret >= 0) {
    kor[ke] = 1;
    if (ret == ke) {
      ko[kv++] = d[ke];
      return -1;
    }
  } else {
    if (kor[h[ke]]) d[ke] = 1;
  }
  return ret;
}
long long gcd(long long a, long long b) {
  if (a < b) swap(a, b);
  if (b == 0) return a;
  return gcd(b, a % b);
}
int main() {
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> h[i];
    h[i]--;
  }
  for (int i = 0; i < n; i++) {
    if (!eler[i]) {
      dfs(i, i + 1);
    }
  }
  int maxx = 0;
  for (int i = 0; i < n; i++) {
    if ((d[i] > maxx) && (!kor[i])) maxx = d[i];
  }
  long long minl = 1;
  for (int i = 0; i < kv; i++) {
    minl = (minl * ko[i]) / gcd(minl, ko[i]);
  }
  long long sol = minl;
  while (sol < maxx) {
    sol += minl;
  }
  cout << sol << endl;
  return 0;
}
