#include <iostream>
#include <fstream>
#include <algorithm>
using namespace std;
int v[100000005];
ifstream fin("nrtri.in");
ofstream fout("nrtri.out");
int main()
{
    int a,c=0;
    fin >>a;
    for (int i=0;i<a;i++)
    {
        fin >>v[i];
    }
    sort (v,v+a);
    for (int i=0;i<a;i++)
    {
        for (int j=i+1;j<a;j++)
        {
            for (int k=j+1;k<a;k++)
            {
                if (v[i]+v[j]>=v[k]&&v[k]+v[j]>=v[i]&&v[i]+v[k]>=v[j]) c++;
            }
        }
    }
   fout << c;
}