#include <iostream>
using namespace std;

class B {
	int i;
public:
	void set_i(int n);
	int get_i();
};

class D : public B {
	int j;
public:
	void set_j(int n);
	int mul();
};

void B::set_i(int n)
{
	i = n;
}

int B::get_i()
{
	return i;
}

void D::set_j(int n)
{
	j = n;
}

int D::mul()
{
	return get_i() * j;
}

int main()
{
	D ob;
	ob.set_i(10);
	ob.set_j(4);
	
	cout << ob.mul() << "\n";
	
	return 0;
}