#include <stdio.h>
#include <algorithm>
using namespace std;

int v[801];
int n, i, j, k;
int total_tr;

int main ()
{
    FILE *f = fopen ("nrtri.in","r");
    FILE *g = fopen ("nrtri.out","w");
    fscanf (f,"%d", &n);
    for (i=1; i<=n; ++i)
        fscanf (f,"%d", &v[i]);

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

    for (i=1; i<=n; ++i)
        for (j=i+1; j<=n; ++j)
        {
            if (i != j)
                for (k=j+1; k<=n; ++k)
                {
                    if (v[i] + v[j] >= v[k] && v[i] + v[k] >= v[j] && v[k] + v[j] >= v[i])
                        total_tr ++;
                    else
                        break;
                }
        }

    fprintf (g, "%d", total_tr);

    fclose (g);
    fclose (f);
    return 0;
}