#include <iostream.h>
#include <fstream.h>

   fstream f("nrtri.in",ios::in);
   fstream g("nrtri.out",ios::out);
   int main ()
     {
     int m, n,a[801],i,j,k=0;
       for (i=1;i<=n;i++)
	  {
	  f>>a[i];
	  }
	for(i=1;i<=n-2;i++)
	for(j=i+1;j<=n-1;j++)
	for(m=j+1;m<=n;m++)
	  {
	   if ((a[i]+a[j])>=a[m] && (a[i]+a[m]>=a[j]) && (a[m]+a[j]>=a[i]))
		k++;
	    }
	    g<<k;
	return 0;
      }