#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 < 800;)
     {
        for(j = 0;j < 800;)
        {
            for(k = 0;k < 800;)
            {
                if(a[i] <= a[j]+a[k])
                {
                    Nr++;
                }
            }
        }
     }
     out<<Nr;
 }