#include <iostream>
#include <algorithm>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <numeric>
#include <bitset>
#include <cmath>

static const int MOD = 1000000007;
using ll = long long;
using u32 = unsigned;
using u64 = unsigned long long;
using namespace std;

template<class T> constexpr T INF = ::numeric_limits<T>::max() / 32 * 15 + 208;

int main() {
    ll n;
    cin >> n;
    ll a = 0, b = 0, ans = n*(n-1)/2;
    for (int i = 0; i < n; ++i) {
        int x;
        scanf("%d", &x);
        if(x == 1) {
            ans += a+b*2;
            a++;
        }
        if(x == 2) {
            ans += a*2;
            b++;
        }
    }
    cout << ans << "\n";
    return 0;
}