#include <iostream>
#define int long long
using namespace std;

int n;
int a[200000];

signed main() {
	int i;
	
	cin >> n;
	for (i = 0; i < n; i++) cin >> a[i];
	
	int len = 0;
	int ans = 0;
	for (i = n - 2; i >= 0; i--) {
		if (len == 0 || a[i] != a[i + 1]) {
			len++;
		}
		else {
			len = 1;
		}
		if (a[i] == 1) { ans += len; }
	}
	
	cout << ans << endl;
	return 0;
}