#include<stdio.h>
#include<algorithm>
using namespace std;
int n,a[800],nr=0;
inline bool tr(int a,int b, int c)
{
	if(a+b>=c&&a+c>=b&&b+c>=a) return true;
	return false;
}
/*int bs(int x,int y)
{
	int i, step;
    for (step = 1;step<n;step<<=1);
    for (i=0;step;step>>= 1)
	{
        if (i+step<n&&tr(a[x],a[y],a[i+step])&&i+step!=x&&i+step!=y)
           i+=step;
	}
	if(!(tr(a[i],a[x],a[y]))) return 0;
    return i;
}*/
int main()
{
	freopen("nrtri.in","r",stdin);
	freopen("nrtri.out","w",stdout);
	scanf("%d",&n);
	for (int i=1;i<=n;i++)
	{
		scanf("%d",&a[i]);
	}
	sort(a,a+n);
	for(int i=1;i<=n-2;i++)
		for(int j=i+1;j<=n-1;j++)
/*			if(bs(a[i],a[j])>=1&&bs(a[i],a[j])<=n)
				nr++;
*/	
				for(int k=j+1;k<=n;k++)
					if(tr(a[i],a[j],a[k])) nr++;
	printf("%d",nr);
	return 0;
}