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