#include <iostream>

class Node
{
public:

    virtual ~Node() = default;
    virtual int eval() const = 0;
    
};

class Number : public Node
{
public:

    Number(int number)
        : number { number }
    {
    }

    int eval() const override
    {
        return number;
    }

private:

    int number;
    
};

class Binary : public Node
{
public:

    Binary(Node& left, Node& right)
        : left { left }, right { right }
    {
    }

protected:

    Node& left;
    Node& right;
    
};

class Addition : public Binary
{
public:

    using Binary::Binary;

    int eval() const override
    {
        return left.eval() + right.eval();
    }
    
};

class Multiplication : public Binary
{
public:

    using Binary::Binary;

    int eval() const override
    {
        return left.eval() * right.eval();
    }
    
};

int main()
{
    Number five{5};
    Number three{3};
    Number two{2};
    Multiplication multiplication{five, two};
    Addition addition{three, multiplication};
    std::cout << addition.eval() << std::endl;
}