/**
 *   @FileName	a.cpp
 *   @Author	kanpurin
 *   @Created	2021.05.17 18:27:51
**/

#include "bits/stdc++.h" 
using namespace std; 
typedef long long ll;

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