[c-prog] friend function member of a class

[mark]

please help me, with this. im getting 2 errors

1. error C2653: 'Anthony' : is not a class or namespace name
2. error C2248: 'Mark::id' : cannot access private member declared in class 
'Mark'

i using visual c++ 2008

here is my code.
----------------------------------------------------------
#include <iostream>

using namespace std;

class Mark
{
public:
        Mark(int x = 900): id(x){}
        friend void Anthony::function(const Mark& mark);
private:
        int id;
};

class Anthony
{
public:
        int x;
        void function(const Mark& mark);
};

void Anthony::function(const Mark& mark)
{
        cout << mark.id << endl;
}
int main()
{
        Mark m(122);
        Anthony b;
        b.function();
        return 0;
}
-----------------------------------------

please help me make this piece of code working..
thanks!!