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