Invalid C++ code, showing wrong attempt to access protected and private members.

erroneous.cpp

#include <iostream>

class EncompassingClass {
    class ProtectedClass;
    static class PrivateClass {
    private:
        int privateMember;
        PrivateClass() {
            privateMember = 1;
        }

        int sum(ProtectedClass pdc) {
            return privateMember + pdc.protectedMember;
        }
    };

    static class ProtectedClass {
    protected:
        int protectedMember;
        ProtectedClass() {
            protectedMember = 1;
        }

        int sum(PrivateClass pec) {
            return protectedMember + pec.privateMember;
        }
    }
};

int main()
{
    std::cout << "Hello World!" << std::endl;
    return 0;
}