#include <iostream>
#include <algorithm>
#include <fstream>
#define MAX 102
using namespace std;
int n,v[MAX],ans;

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

int main()
{
    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 k = j+1; k <= n; k++){
                int a = v[i];
                int b = v[j];
                int c = v[k];
                if(a+c >= b && a+b >= c && b+c >= a){
                    ans++;
                }
            }
        }
    }
    fout << ans << "\n";
    return 0;
}