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

using namespace std;

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

int main()
{
    int n, v[100001], k=0;
    fin>>n;
    for (int i=1; i<=n; i++){
        fin>>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 h=j+1; h<=n; h++){
                if(v[i]+v[j]>=v[h] && v[i]+v[h]>=v[j] && v[j]+v[h]>=v[i]){
                    k++;
                }
            }
        }
    }
    fout<<k;

    return 0;
}