#include <algorithm>
#include <cmath>
#include <iostream>
#include <numeric>
#include <queue>
#include <unordered_map>
#include <vector>
using namespace std;
using ll = long long;
#define rep(i, j, n) for (int i = j; i < (n); ++i)
#define rrep(i, j, n) for (int i = (n)-1; j <= i; --i)
#define all(a) a.begin(), a.end()
template <typename T>
std::ostream &operator<<(std::ostream &os, std::vector<T> &a) {
  for (size_t i = 0; i < a.size(); ++i) os << (i > 0 ? " " : "") << a[i];
  return os << '\n';
}
template <typename T>
std::istream &operator>>(std::istream &is, std::vector<T> &a) {
  for (T &x : a) { is >> x; }
  return is;
}

int main() {
  cin.tie(0)->sync_with_stdio(0);
  int n;
  cin >> n;
  int b;
  unordered_map<int, int> mp;
  vector<ll> fac(n + 1, 1);
  rep(i, 1, n + 1) fac[i] = fac[i - 1] * i;
  rep(i, 0, n) {
    cin >> b;
    ++mp[b];
  }
  ll aa = 1;
  for (auto [k, v] : mp) aa *= fac[v];
  cout << fac[n] / aa;

  return 0;
}