#include <iostream>
#include <fstream>
#include <algorithm>

using namespace std;

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

int main()
{
    int n,a[1005],contor=0;
    f>>n;
    for (int i = 1; i<=n;i ++)
        f>>a[i];

    sort(a+1,a+n+1);

    for (int i=1; i<=n; i++)
        for(int j=i+1; j<=n; j++)
            for (int k=j+i; k<=n; k++)
                if (a[i]+a[j]<a[k]) //&& a[i]+a[k]>=a[j] && a[k]+a[j]>=a[i])
                    contor++;
    g<<contor;

    return 0;
}