#include<fstream>     
using namespace std;     
   
int verificare(int x,int y,int z)  
{  
    if(x+y>=z && x+z>=y && y+z>=x)     
         return 1;  
    else   
         return 0;  
}  
  
int main()     
{     
    ifstream in ("nrtri.in");     
    ofstream out("nrtri.out");     
    int v[801];     
    int n,nr=0,x,y,z;     
    in>>n;     
    for(int i=1;i<=n;++i)     
    in>>v[i];     
    for(int i=1;i<=n-2;++i)     
		for(int j=i+1;j<=n-1;++j)     
            for(int k=j+1;k<=n;++k)     
            {  
                x=v[i];  
                y=v[j];  
                z=v[k];  
                if( verificare(x,y,z) ==1)  
                    nr++;    
            }                     
    out<<nr<<"\n";     
    in.close();     
    out.close();     
    return 0;     
}