#include<fstream.h>
#define input "nrtri.in"
#define output "nrtri.out"
#define Nmax 805
using namespace std;

int main()
	{
	int n,a[Nmax],i,j,k;
	long sol=0;
	ifstream fin(input);
	ofstream fout(output);
	fin>>n;
	for(i=1;i<=n;i++)
		fin>>a[i];
	for(i=1;i<=n;i++)
		for(j=i+1;j<=n;j++)
			for(k=j+1;k<=n;k++)
				if((a[i]+a[j]>=a[k])&&(a[j]+a[k]>=a[i])&&(a[k]+a[i]>=a[j]))
					sol++;
	fout<<sol<<"\n";
	return 0;
	}