#include <stdio.h>
#include <stdlib.h>
int main()
{
    int m,n,i,j,c,a[801];
    freopen("nrtri.in","r",stdin);
    freopen("nrtri.out","w",stdout);
    scanf("%i",&n);
    for (i=1; i<=n; i++) scanf("%i",&a[i]);
    m=0;
    for (i=1; i<=n-2; i++)
    {
     for (j=i+1; j<=n-1; j++)
      {
      for (c=j+1; c<=n; c++)
       if (a[c]+a[i]>=a[j] && a[j]+a[i]>=a[c] && a[c]+a[j]>=a[i]) m++;
      }
    }
    printf("%i",m);
    return 0;
}