#include <fstream>
#include <algorithm>
using namespace std;
ifstream fin ("nrtri.in");
ofstream fout ("nrtri.out");
int X[805];
int main()
{
    int N, i, j, z, t=0;
    fin>>N;
    for (i=1; i<=N; i++)
        fin>>X[i];
    sort (X+1, X+N+1);
    for (i=1; i<=N; i++)
        for (j=i+1; j<=N; j++)
            for (z=j+1; z<=N; z++)
            {
                if (X[z]-X[j]>X[i] && X[z]-X[i]>X[j] && X[i]+X[j]<X[z])
                    break;
                else
                    t++;
            }
    fout<<t<<"\n";
    fin.close();
    fout.close();

    return 0;
}