#include <bits/stdc++.h>
using namespace std;
long long max(long long a, long long b) {
  if (a > b) {
    return a;
  } else {
    return b;
  }
}
long long min(long long a, long long b) {
  if (a < b) {
    return a;
  } else {
    return b;
  }
}
int n, a[301], v[301], q[301], in[301];
int z[301], cnt, w;
long long gcd(long long a, long long b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
long long lcm(long long a, long long b) {
  long long w = gcd(a, b);
  long long p = a / w;
  return p * b;
}
void DFS(int u) {
  in[u]--;
  in[a[u]]--;
  v[a[u]] = max(v[a[u]], v[u] + 1);
  if (in[a[u]] == 0) DFS(a[u]);
}
void DFS2(int id) {
  int y = id;
  int len = 0, p = 0;
  while (in[y] > 0) {
    in[y] = -1;
    len++;
    p = max(p, v[y]);
    y = a[y];
  }
  z[++cnt] = len;
  w = max(w, p);
}
int main() {
  scanf("%d", &n);
  for (int i = (1); i <= (n); i++) in[i] = q[i] = 0;
  for (int i = (1); i <= (n); i++) {
    scanf("%d", &a[i]);
    in[a[i]]++;
    q[i] = 0;
  }
  for (int i = (1); i <= (n); i++) {
    if (in[i] == 0) DFS(i);
  }
  for (int i = (1); i <= (n); i++)
    if (in[i] > 0) DFS2(i);
  long long q = 1;
  for (int i = (1); i <= (cnt); i++) q = lcm(q, z[i]);
  long long ww = q;
  while (q < w) q += ww;
  cout << q << endl;
  return 0;
}
