#include <iostream>
#include <fstream>

using namespace std;

 int main()
 {
     int a[800],i ,j ,k ,n ,Nr = 0;

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

     in>>n;

     for(i=0; i < n;i++)
     {
         in>>a[i];
     }
     for(i = 0;i < n;i++)
     {
        for(j = 0;j < n;j++)
        {
            for(k = 0;k < n;k++)
            {
                if(a[i] <= a[j]+a[k] && a[j] <= a[i] + a[k] && a[k] <= a[i] + a[j])
                {
                     Nr++;
                }
            }
        }
    }
    out<<Nr;
    in.close();
    out.close();
    return 0;
}