/**
 *   @FileName	a.cpp
 *   @Author	kanpurin
 *   @Created	2021.04.11 15:22:59
**/

#include "bits/stdc++.h" 
using namespace std; 
typedef long long ll;

int main() {
    int n;cin >> n;
    vector<ll> cnt(3,0);
    for (int i = 0; i < n; i++) {
        int a;cin >> a;
        if (a >= 3) cnt[2]++;
        else if (a == 2) cnt[1]++;
        else cnt[0]++;
    }
    cout << 2 * cnt[0] * cnt[2] + 2 * cnt[0] * (cnt[0]-1)/2 + 3 * cnt[0] * cnt[1] + cnt[1] * (cnt[1]-1)/2+cnt[1] * cnt[2] + cnt[2] * (cnt[2]-1) / 2 << endl;
    return 0;
}