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


int main() {
    int n;
    cin >> n;
    vector<int> emp, fil, b(n);
    for (int i=0; i<n; ++i) {
        cin >> b[i];
        if (b[i]) fil.push_back(i);
        else emp.push_back(i);
    }
    int i = 0, j = 0;
    int ans = 0;
    while (i < emp.size()) {
        while (b[fil[j]]<=1) j++;
        ans += abs(emp[i]-fil[j]);
        i++;
    }
    cout << ans << endl;
}