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

int main() {
	long long N; cin >> N;
	vector<long long> A(N); for (int i = 0; i < N; i++) cin >> A[i];

	long long max_ = 0;
	long long sum = 0;
	for (int i = 0; i < N; i++) {
		if (A[i] == 0) max_ = i + 1;
		sum += max_;
	}

	cout << sum << endl;
}