#include <iostream>
#include <fstream>

using namespace std; 

ifstream f("nrtri.in");

ofstream g("nrtri.out");


unsigned int N, v[800], i, j, k;

unsigned long nr; 

int main()

{
	f >> N; nr = 0; 

	for (i = 0; i <= N-1; i++)  f >> v[i]; 

	for (i = 0; i <= N - 1; i++) for (j = i + 1; j <= N - 1; j++)  for (k = j + 1; k <= N - 1; k++)     if (v[i] + v[j] >= v[k] && v[i] + v[k] >= v[j] && v[k] + v[j] >= v[i]) nr++; 

	g << nr; 

	return 0; 





}