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