#include <bits/stdc++.h>
using namespace std;

long long x, y, z;
int main() {
	int n;
	cin >> n;
	vector a(n, 0);
	for(auto& v : a) cin >> v;
	x = count(a.begin(), a.end(), 1);
	y = count(a.begin(), a.end(), 2);
	z = n - x - y;
	cout << x * y * 3 + x * (x - 1) / 2 * 2 + z * (n - x) / 2 << endl;
	return 0;
}