#include <iostream>
#include <fstream>
using namespace std;
ifstream f("nrtri.in");
ofstream g("nrtri.out");
int main()
{
    int n,a[30001],s=0;
    f>>n;
    for (int i=0;i<n;i++)
    {
        f>>a[i];
    }
    for (int i=0;i<n-2;i++)
    {
        for (int j=i+1;j<n;j++)
        {
            for (int k=j+1;k<n;k++)
                if ((a[i]+a[j]>=a[k])&&(a[j]+a[k]>=a[i])&&(a[i]+a[k]>=a[j]))
                     s++;
        }
    }
    g<<s;
    return 0;
}