#include<fstream>
using namespace std;
ifstream f("nrtri.in");
ofstream g("nrtri.out");
int main(){
int i,a[100],n,m=0,j,k;
f>>n;
for (i=1;i<=n;i++) f>>a[i];
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]&&a[j]+a[k]>=a[i]&&a[i]+a[k]>=a[j]) m+=1;
g<<m;
f.close();
g.close();
return 0;}