#include<bits/stdc++.h>
using namespace std;
#define int long long
signed main(){
  int N;cin>>N;
  vector<int>vec(N);
  map<int,int>mp;
  for(int &i:vec){
    cin>>i;
    mp[i]++;
  }
  int ans=0,memo=0;
  ans+=mp[1]*mp[2]*3;
  memo+=mp[1]*mp[2];
  ans+=(mp[1]*(mp[1]-1)/2+mp[1]*(N-mp[1]-mp[2]))*2;
  memo+=(mp[1]*(mp[1]-1)/2+mp[1]*(N-mp[1]-mp[2]));
  ans+=N*(N-1)/2-memo;
  cout<<ans<<endl;
}