#include <bits/stdc++.h>
using namespace std;
long long GCD(long long a, long long b) {
  if (!a) return b;
  return GCD(b % a, a);
}
int n;
std::vector<int> f, vis, cyc;
int dfs(int at, int from) {
  if (vis[at]) {
    if (at == from) {
      return 0;
    } else
      return -(1 << 29);
  }
  vis[at] = true;
  return dfs(f[at], from) + 1;
}
int go(int at) {
  if (cyc[at] != -1) {
    return 0;
  }
  return go(f[at]) + 1;
}
long long LCM(long long a, long long b) {
  long long g = GCD(a, b);
  return (a / g) * b;
}
int main() {
  clock_t startTime = clock();
  ios_base::sync_with_stdio(false);
  cin >> n;
  f.push_back(0);
  for (int i = (0); i < (int)(n); i++) {
    int z;
    cin >> z;
    f.push_back(z);
  }
  long long ans = 1;
  cyc.resize(n + 1, 0);
  for (int i = (1); i < (int)(n + 1); i++) {
    vis.clear();
    vis.resize(n + 1, 0);
    int l = dfs(i, i);
    if (l > 0) {
      ans = LCM(ans, l);
      cyc[i] = l;
    } else {
      cyc[i] = -1;
    }
  }
  int mx = 1;
  for (int i = (1); i < (int)(n + 1); i++) {
    if (cyc[i] == -1) {
      mx = max(mx, go(i));
    }
  }
  cerr << mx << "\n";
  ans = ((mx / ans) + !!(mx % ans)) * ans;
  cout << ans << "\n";
  clock_t endTime = clock();
  cerr << "\nTime:" << double(endTime - startTime) / CLOCKS_PER_SEC
       << " seconds\n";
  return 0;
}
