#include <bits/stdc++.h>
using namespace std;
using ll=long long;
#define rep(i,n) for(int i=0; i<(n); i++)

ll N;
ll c1,c2,cx;

int main(){
  cin>>N;
  c1=c2=cx=0;
  rep(i,N){
    int a; cin>>a;
    if(a==1) c1++;
    if(a==2) c2++;
    if(a>2) cx++;
  }
  ll ans=0;
  ans += c1*(c1-1)/2 *2;
  ans += c1*c2 *3;
  ans += c1*cx *2;
  ans += c2*(c2-1)/2 *1;
  ans += c2*cx *1;
  ans += cx*(cx-1)/2 *1;
  cout<<ans<<"\n";
  return 0;
}