#include<bits/stdc++.h>
#define int long long
#define matsuri pair<int,int>
//const int iris = 1e9+7;
const int iris = 998244353;
using namespace std;

void solve()
{
	int n;
	cin>>n;
	int cnt=0, ans=n*(n+1)/2;
	while(n--)
	{
		int a;
		cin>>a;
		if(a)
		{
			cnt++;
			ans-=cnt;
		}
		else
		{
			cnt=0;
		}
	}
	cout<<ans<<'\n';
}

signed main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);

	int T=1;
	//cin>>T;
	while(T--)
		solve();

	return 0;
}