#include <iostream>

using namespace std;

class Letter{
private:
    char c;
public:
    Letter(char a){
        c = a;
    }

    void print(){
        cout << c << endl;
    }

    void changeTo(char a){
        c = a;
    }

    char toLowerCase(){
        return tolower(c);
    }

    char toUpperCase(){
        return toupper(c);
    }

    bool isVowel() {
        char ch = tolower(c);
        if(ch=='a' || ch=='e' || ch=='i' || ch=='o' || ch=='u' || ch == 'y')
            return true;
        else return false;
    }
};

int main() {
    Letter a('a');

    Letter b('B');

    cout << a.isVowel() << endl;
    cout << b.isVowel() << endl;
    cout << a.toUpperCase() << endl;
    cout << b.toLowerCase() << endl;



    return 0;
}