// ConsoleApplication1.cpp : This file contains the 'main' function. Program execution begins and ends there.

// Run program: Ctrl + F5 or Debug > Start Without Debugging menu
// Debug program: F5 or Debug > Start Debugging menu

// Tips for Getting Started: 
//   1. Use the Solution Explorer window to add/manage files
//   2. Use the Team Explorer window to connect to source control
//   3. Use the Output window to see build output and other messages
//   4. Use the Error List window to view errors
//   5. Go to Project > Add New Item to create new code files, or Project > Add Existing Item to add existing code files to the project
//   6. In the future, to open this project again, go to File > Open > Project and select the .sln file

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

using namespace std;

ifstream acin("nrtri.in");
ofstream acout("nrtri.out");

int main(){
    int n,v[801],c=0;
    acin >> n;
    for (int i = 1; i <= n; i++) {
        cin >> v[i];
    }
    sort(v + 1, v + n + 1);
    for (int i = 1; i <= n; i++) {
        for (int j = i + 1; j <= n; j++) {
            for (int k = j + 1; k <= n; k++) {
                if (v[i] + v[j] >= v[k]) {
                    c++;
                }
            }
        }
    }
    acout << c;
}