#include <fstream>
#include <algorithm>

using namespace std;
 
ifstream cin ("nrtri.in");
ofstream cout ("nrtri.out");
 
int main()
{
	int v[801], i, j, k, s=0, n;
	cin>>n;
	for(i=0;i<n;i++)
		cin>>v[i];
	sort(v,v+n);
	for(i=0;i<n-2;i++)
		for(j=0;j<n-1;j++)
			for(k=0;k<n;k++)
				if(v[k]<=v[i]+v[j])
					s++;
				else
					break;
	cout<<s;
}