#include <iostream>

class BaseClass {
public:
    BaseClass() {
        call();
    }
    virtual void call() {
        std::cout << "BaseClass!";
    }
};

class SubClass : public BaseClass {
public:
    SubClass() : BaseClass()
    {
    }

    void call() {
        std::cout << "SubClass!";
    }
};

int main()
{
    SubClass x;
}