#include <iostream>

using namespace std;
using lint = long long;

void solve() {
    int n;
    cin >> n;

    lint ans = lint(n) * (n + 1) / 2;
    int prev = -1;
    for (int i = 0; i < n; ++i) {
        int x;
        cin >> x;

        if (x == 0) {
            lint m = i - prev - 1;
            ans -= m * (m + 1) / 2;
            prev = i;
        }
    }

    {
        lint m = n - prev - 1;
        ans -= m * (m + 1) / 2;
    }

    cout << ans << "\n";
}

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    solve();

    return 0;
}