#include<fstream.h>
long long a[50000],n,i,j,k,nr;
int main()
{
  ifstream f("nrtri.in");
  ofstream g("nrtri.out");
   f>>n;
    for(i=1;i<=n;i++)
     f>>a[i];
     i=1;
   while(i<=n-2)
    {
     j=i+1;
     while(j<=n-1)
      {
       k=j+1;
	while(k<=n)
	 {
	  if((a[i]+a[j]>=a[k])&&(a[i]+a[k]>=a[j])&&(a[j]+a[k]>=a[i]))
	   nr++;
	  k++;
	  }
        j++;
       }
      i++;
     }
   g<<nr;
  return 0;
}