#include <fstream>
#include <algorithm>
using namespace std;
ifstream cin ("nrtri.in");
ofstream cout ("nrtri.out");
int v[805], cnt=0;
int main()
{
   int n;
   cin>>n;
   for (int i=1; i<=n; i++)
    {
        cin>>v[i];
    }
    sort(v+1,v+n+1);
   for (int i=1; i<=n; i++)
   {
       for (int j=i+1; j<=n; j++)
       {
           for (int k=j+1; k<=n; k++)
           {
               if (v[k]<=v[i]+v[j] && v[i]<=v[k]+v[j] && v[j]<=v[i]+v[k])
                 cnt++;
           }
       }
   }
   cout<<cnt;
    return 0;
}