facade

#include <iostream>
#include<math.h>
using namespace std;

class desktop
{
public:
    void on() {
        cout << "power on\n";
    }
    void off() {
        cout << "power off\n";
    }
    void notebook() {
        cout << "open notebook\n";
    }
    void sum() {
        int a, b;
        cin >> a >> b;
        cout << a + b<<'\n';
    }
    void sqr() {
        int i;
        cin >> i;
        cout << sqrt(i);

    }
};


class Facade
{
public:

    desktop cur;
    void operation() {
        cout << "0-power on\n 1 - sum\n 2 - sqrt\n 3 - notebook\n 4 - power off\n";
        int status;
        cin >> status;
        if (status == 0)
            cur.on();
        if (status == 1)
            cur.sum();
        if (status == 2)
            cur.sqr();
        if (status == 3)
            cur.notebook();
        if (status == 4)
            cur.off();
    }
};

int main()
{
    while (1) {
        Facade PC;
        PC.operation();
    }


}