#include <iostream>
#include <fstream>
using namespace std;
ifstream f("nrtri.in");
ofstream g("nrtri.out");
int a[801],i,j,z,n,k,kk,ok;
void quickSort(int a[], int left, int right)
{
      int i = left, j = right;
      int tmp;
      int pivot = a[(left + right) / 2];
      while (i <= j) {
            while (a[i] < pivot)
                  i++;
            while (a[j] > pivot)
                  j--;
            if (i <= j) {
                  tmp = a[i];
                  a[i] = a[j];
                  a[j] = tmp;
                  i++;
                  j--;
            }
      };
      if (left < j)
            quickSort(a, left, j);
      if (i < right)
            quickSort(a, i, right);
}
int main()
{
    f>>n;
    for(i=1;i<=n;i++)
        f>>a[i];
    quickSort(a,1,n);
    for(i=1;i<n;i++)
        for(j=i+1;j<n;j++)
         {
             //ok=0;
             for(z=j+1;z<=n;z++)
             {
                 if(a[z]>a[i]+a[j])
                 {
                     //ok=1
                     kk++;
                 }
             }

         }
    g<<kk;
    return 0;
}