#include <iostream>
    using namespace std;
    class Example
    {
        public:
        Example(int k) : num_k(k) { }
        public:
        int operator()(int k = 0) const 
        { 
            return num_k + k; 
        }
        operator int () const   
        { 
            return num_k; 
        }
        private:
        int num_k;
        friend int g(const Example&);
    };
    int fun(char Z)
    {
        return Z;
    }
    int main()
    {
        Example fun(6);
        cout << fun(5);
        return 0;
    }