#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 non_zero_seg_cnt = 0;
	int len = 0;
	for (i = 0; i < n; i++) {
		if (a[i] == 0) {
			non_zero_seg_cnt += len * (len + 1) / 2;
			len = 0;
		}
		else {
			len++;
		}
	}
	non_zero_seg_cnt += len * (len + 1) / 2;
	
	int ans = n * (n + 1) / 2 - non_zero_seg_cnt;
	cout << ans << endl;
	return 0;
}