#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;

#define ll long long
#define rep(i, n) for (int i = 0; i < (n); i++)
#define P pair<int, int>
#define LP pair<ll, ll>
#define fi first
#define se second
#define pb push_back
#define eb emplace_back
#define all(s) s.begin(), s.end()
#define rall(s) s.rbegin(), s.rend()
template<class T>
void chmax(T& a, T b) { a = max(a, b); };
template<class T>
void chmin(T& a, T b) { a = min(a, b); };

int main() {
  int n;
  cin >> n;
  vector<int> a(n);
  rep(i,n) cin >> a[i];
  map<int,int> mp;
  rep(i,n) mp[a[i]]++;
  ll ans = 1;
  for (ll i = 1; i <= n; i++) ans *= i;
  for (auto it : mp) {
    for (ll i = 1; i <= it.second; i++) {
      ans /= i;
    }
  }
  cout << ans << endl;

  

  return 0;
}