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