class Zsak
{
    public:
        Zsak();
        ~Zsak();
        void Add( int x );
        friend ostream& operator<< (std::ostream& os, Zsak& zs);
        friend Zsak operator+( const Zsak &a, const Zsak &b );
    private:
        list<int> zs;
};

std::ostream& operator<< (std::ostream& os, Zsak& zs)
{
    list<int>::iterator i;

    for( i = zs.zs.begin(); i != zs.zs.end(); i++ )
        os << *i << " ";
    return os;
}

Zsak operator+( const Zsak &a, const Zsak &b )
{
    Zsak ret;

    list<int>::iterator i;

    for( i = a.zs.begin(); i != a.zs.end(); i++ )
        ret.Add( *i );
}