#include <iostream>
#include <memory>

using namespace std;

auto main() -> int {

    struct A {
        virtual void dosmth() = 0;
    };

    struct B : A {
        virtual void dosmth() override {
            cout << 332 << endl;
        }
    };

    A *obj = new B();

    obj->dosmth();
    B *elm = dynamic_cast<B*>(obj);
}