#include <iostream>
#include <fstream>

using namespace std;

ifstream f("nrtri.in");
ofstream g("nrtri.out");

int main()
{
    int n,aa[801],a,b,c,k = 0;

    f >> n;

    for(int i = 1;i <= n;i++)
    {
        f >> aa[i];
    }

    for(int i = 1;i <= n - 2;i++)
    {
        for(int j = i + 1;j <= n - 1;j++)
        {
            for(int o = j + 1;o <= n;o++)
            {
                a = aa[i];
                b = aa[j];
                c = aa[o];
                if((a + b >= c) && (a + c >= b) && (c + b >= a))
                {
                    k++;
                }
            }
        }
    }

    g << k;




    return 0;
}