#include<iostream.h>
#include<fstream.h>
int x,a[801];
void triunghi(int i, int j, int k)
{
	if(a[i]+a[j]>=a[k] && a[i]+a[k]>=a[j] && a[j]+a[k]>=a[i])
		x++;
}
int main()
{
	fstream f("nrtri.in", ios::in);
	fstream g("nrtri.out", ios::out);
	int N,i,j,k;
	f>>N;
	for(i=1;i<=N;i++)
		f>>a[i];
	for(i=1,x=0;i<=N;i++)
		for(j=i+1;j<=N;j++)
			for(k=j+1;k<=N;k++)
				triunghi(i,j,k);
	g<<x;
}