#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>

using namespace std;

ifstream fin("nrtri.in");
ofstream fout("nrtri.out");

int n, v[803];

int main()
{
    fin >> n;
    for (int i = 0, x; i < n; i++)
        fin >> v[i];
    sort(v, v+n);


    int res = 0;
    for (int i = 0; i < n - 2; i++)
    {
        for (int j = i + 1; j < n - 1; j++)
        {
            for (int k = j + 1; k < n; k++)
            {
                if (v[i] + v[j] >= v[k] && v[i] + v[k] >= v[j] && v[j] + v[k] >= v[i])
                    res++;
            }
        }
    }
    fout << res;

    return 0;
}