#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
using ll=long long;
using Graph=vector<vector<int>>;
#define INF 1000000000
#define MOD 998244353
#define MAX 1000

int main(){
  int N;
  cin>>N;
  vector<int> A(N);
  for(int i=0;i<N;i++){
    cin>>A[i];
  }
  sort(A.begin(),A.end());
  ll sum=1;
  int i=0;
  while(i<N){
    int x=A[i];
    int cnt=0;
    while(i<N&&x==A[i]){
      cnt++;
      i++;
    }
    while(cnt>0){
      sum*=(ll)cnt;
      cnt--;
    }
  }

  ll x=1;
  for(int i=1;i<=N;i++){
    x*=(ll)i;
  }
  cout<<x/sum<<'\n';
}