#include <iostream>
#include <vector>
 
class A
{
	public:
		virtual void print() const { std::cout << "I'm an A!" << std::endl; }
};
 
class B : public A
{
	public:
		void print() const { std::cout << "I'm a B!" << std::endl; }
};
 
int main() {
	std::vector<A> v;
	std::vector<A*> vv;
 
	v.push_back(A());
	v.push_back(B());
 
	for(const auto& x : v)
	{
		x.print();
	}
 
	vv.push_back(new A);
	vv.push_back(new B);
 
	for(const auto& x : vv)
	{
		x->print();
	}
 
	return 0;
}

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