// 2022 IUSB Programming Competition
// Round 1 Problem 5
// Triamgles
// Solution by Liguo Yu

#include <iostream>
using namespace std;

int formTriangles(int * a, int size);

int main()
{
	int m;
	cin >> m;

	int * a = new int[m];

	for (int i = 0; i < m; i++)
	{
		cin >> a[i];
	}

	cout << formTriangles(a, m);
  return 1;
}

int formTriangles(int * a, int size)
{
	int result = 0;

	for (int i = 0; i < size; i++)
	{
		for (int j = i + 1; j < size; j++)
		{
			for (int k = j + 1; k < size; k++)
			{
				if (a[i] + a[j] > a[k] && a[i] + a[k] > a[j] && a[j] + a[k] > a[i])
				{
					result = result + 1;
				}
			}
		}
	}

	return result;
}