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

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

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

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++){
            ans += binsearch(i, j);
        }
    }
    fout << ans << "\n";
    return 0;
}