#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 binsearch(int i, int j){
    int t,step;
    int val = v[i]+v[j];
    for(step = 1; step <= n; step <<= 1);
    for(t = 1; step; step >>= 1){
        if(t+step <= n && v[t+step] <= val){
            t += step;
        }
    }
    return t-j;
}

int main()
{
    cin >> 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++){
            ans += binsearch(i, j);
        }
    }
    cout << ans << "\n";
    return 0;
}