#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <cmath>
#include <map>
#include <queue>
#include <iomanip>
#include <set>
#include <tuple>
#define mkp make_pair
#define mkt make_tuple
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define all(v) v.begin(),v.end()
using namespace std;
typedef long long ll;
const ll MOD=1e9+7;
template<class T> void chmin(T &a,const T &b){if(a>b) a=b;}
template<class T> void chmax(T &a,const T &b){if(a<b) a=b;}

int main(){
  cin.tie(0);
  ios::sync_with_stdio(false);

  ll N;
  cin>>N;
  vector<int> A(N);
  rep(i,N) cin>>A[i];

  ll one=0,two=0;
  rep(i,N){
    if(A[i]==1) one++;
    else if(A[i]==2) two++;
  }

  ll s3=one*two;
  ll s2=one*(N-two-one)+one*(one-1)/2;
  ll s1=N*(N-1)/2-s3-s2;

  ll ans=0;
  ans+=3*s3;
  ans+=2*s2;
  ans+=1*s1;
  cout<<ans<<endl;

  return 0;
}