#include <iostream>
#include <cstdlib>

using namespace std;

class Radio {
    private:
        double frequency;

    public:
        double get() {
            return frequency;
        }
        void set(double f){
            // Valid frequency.
            if(f>=88 && f<=108)
                frequency=f;
            else {
                cout << "Invalid Frequency \a" << f;
                exit(1);
            }
        }
};
int main () {
    Radio radio;
    double station;

    cout << "What radio station do you want? ";
    cin >> station;

    radio.set(station);
    cout << "Radio is tuned to: " << radio.get();
}