#include<fstream.h>
int main()
{
	 int n,i,j,l,k,v[1000];
	 ifstream f("nrtri.in");
	 ofstream g("nrtri.out");
	 f>>n;
	 k=0;
	 for(i=1;i<=n;i++)f>>v[i];
	 for(i=1;i<=n-2;i++)
		  for(j=i+1;j<n;j++)
			  for(l=j+1;l<=n;l++)
			   if((v[i]+v[j]>=v[l])&&(v[i]+v[l]>=v[j])&&(v[l]+v[j]>=v[i]))k++;
     g<<k;
     f.close();
     g.close(); 
     return 0;
}