#include<fstream>
#include<algorithm>
using namespace std;
ifstream f("nrtri.in");
ofstream g("nrtri.out");
short k,j,a[801],i,n;
int nr;
void solve()
{
	for(i=1;i<=n-2;i++)
		for(j=i+1;j<=n-1;j++)
			for(k=j+1;k<=n;k++)
			{
				if(a[i]+a[j]>=a[k])++nr;
				
					
			}
			g<<nr<<'\n';
}
int main()
{
	f>>n;
	for(i=1;i<=n;i++)
		f>>a[i];
	sort(a+1,a+n+1);
	solve();
	return 0;
}