#include <fstream>
using namespace std;
int main()
{
	ifstream f("nrtri.in");
	ofstream g("nrtri.out");
	int i,v[3001],n,a,b,c,j,q,K,x;
	f>>n; K=0;
	for (i=1;i<=n;i++)
	{
		f>>x;
		v[i]=x;
	}
	for (i=1;i<=n;i++)
	{
		a=v[i];
		for (j=i+1;j<=n-1;j++)
		{
			b=v[j];
			for (q=j+1;q<=n;q++)
			{
				c=v[q];
				if (a<=b+c&&b<=c+a&&c<=a+b) K++;
			}
		}
	}
	g<<K;
	f.close();g.close();return 0;
}