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

int main() {
    int N;
    cin >> N;
    vector<int> A(N);
    for (auto&& a : A) {
        cin >> a;
    }
    long long ans = 1ll * N * (N + 1) / 2;
    int len = 0;
    A.emplace_back(0);
    for (auto&& a : A) {
        if (a == 1)
            len++;
        else {
            ans -= 1ll * len * (len + 1) / 2;
            len = 0;
        }
    }
    cout << ans << endl;
}