#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;++i)   
        for(int j=i+1;j<=n;++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;   
}