#include<fstream.h>
int n,i,j,v[801];
int outOfBorders,mijBun,stanga,dreapta;

int q_sort(int a[], int l,int r)
{  int i,j;
	 i=l;    j=r;

  int ref,temp;
    ref=a[(l+r)/2];
    do {
  while(a[i]<ref&& i<r)
  i++;
  while(ref<a[j]&& j>l)
  j--;
  if(i<=j)
   {  temp=a[i];
       a[i]=a[j];
       a[j]=temp;
       i++;
       j--;           }
	  } while (i<=j);
  if (l<j) q_sort(a,l,j);
  if (i<r) q_sort(a,i,r);
  return 0;         }

int main()
{
ofstream out("nrtri.out");
int cnt=0,x,tzi;
ifstream in("nrtri.in");
in>>n;
for(i=1;i<=n;i++)
	in>>v[i];
in.close();


int tzzz;
q_sort(v,1,n);
for(i=1;i<n;i++)
	for(j=i+1;j<=n;j++)
		{
		x=v[i]+v[j];
		for(tzzz=j+1;tzzz<=n;tzzz++)
			if(v[tzzz]<=x) cnt++;
		}

out<<cnt<<'\n';
out.close();
return 0;
}