#include <iostream>
#include <vector>
#include <cstring>
#include <algorithm>
#include <map>
using namespace std;
int main(){
    long long n;
    cin>>n;
    int niza[n];
    for(int i = 0; i < n; i++){
        cin>>niza[i];
    }
    long long sz = 0;
    long long answer = 0;
    long long prev_zero = -1;
    for(int i = 0; i < n; i++) {
        if(niza[i] == 0) {
            answer += (long long)(i - prev_zero) * (long long)(n - i);
            prev_zero = i;
        }
    }
    cout << answer << endl;

    return 0;
}

/*
5
 4, 2, 0, 1, 3

 **/