#include <cstdio>
#include <algorithm>
using namespace std;
int a[805];
int main () {
	int n, i, j, k, c=0,x,min;
	freopen("nrtri.in","r",stdin);
	freopen("nrtri.out","w",stdout);
	scanf("%d",&n);
	for(i=1; i<=n; ++i){
		scanf("%d",&a[i]);
	}
	sort(a+1,a+n+1);
		
	for(i=n; i>2; --i){
		min=1;
		x=0;
		for(;a[min]+a[i-1]<a[i]&&min<i-1;){
			x=x+1;
			min=min+1;
		}
		c=c+i-2-x;
	}
			
	printf ("%d",c);
	 return 0;
}