#include<stdio.h>
struct Nod {
	long n;
	Nod* urm;
};
void adaug_ultim(Nod* &ultim, int x) {
	Nod* p = new Nod;
	p->n = x;
	p->urm = NULL;
	ultim->urm = p;
	ultim=p;
	       }
int main () {

freopen("nrtri.in","r",stdin);
freopen("nrtri.out","w",stdout);

	long numar=0;

	Nod* p = NULL, *prim = NULL,*q=NULL,*r=NULL;
	int i,n;
        long x;

	scanf("%ld",&n);
	scanf("%ld",&x);

	adaug_ultim(p,x);
	prim=p;


	for(i=1;i<n;i++){
	    scanf("%ld",&x);
	      adaug_ultim(p,x);

		      }

	for(p=prim;(p->urm)->urm!=NULL;p=p->urm)

	 for(q=p->urm;q->urm!=NULL;q=q->urm)

	  for(r=q->urm;r!=NULL;r=r->urm)
	  if((p->n+q->n >= r->n)&&(p->n+r->n >= q->n)&&(q->n+r->n >= p->n)) numar++;

     printf("%ld",numar);
return 0;
}