#include<fstream>
using namespace std;
ifstream f("nrtri.in");
ofstream g("nrtri.out");   
int n,i,j,k,s[805],aux,c=0;
int main() {
	f>>n;
	for(i=1;i<=n;i++)
	f>>s[i];
	for(i=1;i<=n;i++)
		for(j=i+1;j<=n;j++) if(s[i]>s[j]){
			aux=s[i];
			s[i]=s[j];
			s[j]=aux;
		}
	for(i=1;i<=n;i++) for(j=i+1;j<=n;j++) for(k=j+1;k<=n;k++) if(s[i]+s[j]>=s[k]) c++;
	g<<c;
    return 0;
}