#include<fstream> 
#include<algorithm> 
using namespace std; 
int v[999],n,i,q,k,j; 
int main() 
{ 
	ifstream fin("nrtri.in");
	fin>>n; 
	for(i=1;i<=n;i++) 
		fin>>v[i]; 
	sort(v+1,v+n+1); 
	for(i=1;i<n-1;i++) 
		for(j=i+1;j<n;j++) 
			for(k=j+1;k<=n;k++) 
				if(v[i]+v[j]>=v[k]) 
					q++; 
				else break; 
				ofstream fout("nrtri.out");
				fout<<q; 
return 0; 
}