#include<iostream.h>
#include<fstream.h>
main()
{long n,i,j,k,x=0,a[1000];
fstream f("nrtri.in",ios::in);
fstream g("nrtri.out",ios::out);
f>>n;
for(i=1;i<=n;i++)
	f>>a[i];
for(i=1;i<n-1;i++)
	for(j=i+1;j<n;j++)
   	for(k=j+1;k<=n;k++)
      	if((a[i]+a[j]>=a[k])||(a[i]+a[k]>=a[j])||(a[k]+a[j]>=a[i]))
         	x++;
g<<x;
f.close();
g.close();
return 0;
}