#include <iostream>
#include <vector>
using namespace std;
int main(){
    int N;
    cin >> N;
    vector<int> A(N);
    for(int i = 0; i < N; i++) cin >> A[i];
    long long ans = 0;
    long long zero = -1;
    for(int i = 0; i < N; i++){
        if(A[i] == 0) zero = i;
        if(A[i] == 0) ans += i + 1;
        else ans += zero + 1;
    }
    cout << ans << endl;
}