# include <fstream.h>
ifstream f("nrtri.in");
ofstream g("nrtri.out");
int n,i,v[100],aux,j,nr;
int main (){
f>>n;
for (i=1;i<=n;i++)
    f>>v[i];
for (i=1;i<n;i++)
   for (j=i+1;j<=n;j++)
       if (v[i]>=v[j]){
	  aux=v[i];
	  v[i]=v[j];
	  v[j]=aux;}
nr=0;
for (i=1;i<n-1;i++)
    for ( j=i+2;j<=n;j++)
	    if (v[i]+v[i+1]>=v[j])
		nr++;
g<<nr;

return 0;}