#include<fstream>
using namespace std;
ifstream cin("nrtri.in");
ofstream cout("nrtri.out");   
int n,a,b,c,q[805],aux,p=0;
int main()
{ 
     cin>>n;
     for(a=1;a<=n;a++)
     cin>>q[a];
    for(a=1;a<=n;a++)
   for(b=a+1;b<=n;b++)
    if(q[a]>q[b]){aux=q[a];q[a]=q[b];q[b]=aux;} 
   
      for(a=1;a<=n;a++)
      for(b=a+1;b<=n;b++)
      for(c=b+1;c<=n;c++)
      if(q[a]+q[b]>=q[c])
      p++;
      cout<<p;   
    return 0;
}