#include<iostream>
using namespace std;
int N;
int A[2<<17];
main()
{
	cin>>N;
	for(int i=0;i<N;i++)cin>>A[i];
	long ans=(long)N*(N+1)/2;
	for(int i=0;i<N;)
	{
		if(A[i]==0)
		{
			i++;
			continue;
		}
		int r=i;
		while(r<N&&A[r]==1)r++;
		int len=r-i;
		i=r;
		ans-=(long)len*(len+1)/2;
	}
	cout<<ans<<endl;
}