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

import java.util.Scanner;

public class round1_p5
{	
    public static void main(String[] args)
    {
        Scanner input = new Scanner(System.in);
        int m = input.nextInt();
        
        int[] a = new int[m];
        for(int i=0; i<m; i++)
        {
            a[i] = input.nextInt();
        }
        
        System.out.println(formTriangles(a));
    }
    
    public static int formTriangles(int[] a)
    {       
        int result = 0;
        
        for(int i=0; i<a.length; i++)
        {
            for(int j = i+1; j<a.length; j++)
            {
                for(int k = j+1; k<a.length; 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;
    }
}