#include <iostream>
#include <cstdint>
#include <vector>
#include <algorithm>

using namespace std;

int main()
{
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	
	int32_t N, i;
	cin >> N;
	vector<int32_t> A(N);
	for (i = 0; i != N; ++i) cin >> A[i];

	int32_t count_1 = 0, count_2 = 0;
	for (i = 0; i != N; ++i)
		switch (A[i])
		{
		case 1:
			++count_1;
			break;

		case 2:
			++count_2;
			break;
		}

	cout << N * static_cast<int64_t>(N - 1) / 2 + count_1 * static_cast<int64_t>(count_1 - 1) / 2 + count_1 * static_cast<int64_t>(count_2) * 2 << '\n';
	return 0;
}