class con: public Expression {
private:
    int x;

public:
    con(int a) {
        x = a;
    }
    int Evaluate() const {
        return x;
    }
    std::string ToString() const {
        return std::to_string(x);
    }
};

class sum : public Expression {
private:
    ExpressionPtr x;
    ExpressionPtr y;

public:
    sum(ExpressionPtr a, ExpressionPtr b) : x(a), y(b) {}

    int Evaluate() const {
        return x->Evaluate() + y->Evaluate();
    }
    std::string ToString() const {
        return (x->ToString() + " + " + y->ToString());
    }
};

class product : public Expression {
private:
    ExpressionPtr x;
    ExpressionPtr y;

public:
    product(ExpressionPtr a, ExpressionPtr b) : x(a), y(b) {}

    int Evaluate() const {
        return x->Evaluate() * y->Evaluate();
    }
    std::string ToString() const {
        std::string e1 = x->ToString();
        std::string e2 = y->ToString();
        size_t summ = e1.find('+');
        size_t left = e1.find('(');
        if (summ != -1) {
            if (left == -1 || (left != -1 && (summ < left || e1.rfind('+') > e1.rfind(')')))) {
                e1 = "(" + e1 + ")";
            }
        }
        summ = e2.find('+');
        left = e2.find('(');
        if (summ != -1) {
            if (left == -1 || (left != -1 && (summ < left || e2.rfind('+') > e2.rfind(')')))) {
                e2 = "(" + e2 + ")";
            }
        }
        return e1 + " * " + e2;
    }
};

ExpressionPtr Const(int a) {
    return ExpressionPtr(new con(a));
}

ExpressionPtr Sum(const ExpressionPtr& a, const ExpressionPtr& b) {
    return ExpressionPtr(new sum(a, b));
}

ExpressionPtr Product(const ExpressionPtr& a, const ExpressionPtr& b) {
    return ExpressionPtr(new product(a, b));
}