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

void fast_io() {
	ios_base::sync_with_stdio(false);
	cin.tie(nullptr);
}

int main() {
	fast_io();
	int n;
	cin >> n;
	long long cnt[2] = {0, 0};
	for (int i = 0; i < n; i++) {
		int a;
		cin >> a;
		if (a <= 2) {
			cnt[a - 1]++;
		}
	}
	long long ans = (long long)n * (n - 1);
	ans -= (n - cnt[0]) * (n - cnt[0] - 1) / 2;
	ans += cnt[0] * cnt[1];
	cout << ans << endl;
}