#include <bits/stdc++.h>

using namespace std;
using ll = long long;

int main(){

    ll N, A, ans=0, l=-1;
    cin >> N;

    for (int i=0; i<N; i++){
        cin >> A;
        if (A == 0) l=i;
        ans += l+1;
    }

    cout << ans << endl;

    return 0;
}