import java.util.ArrayDeque;
public class Mono {
    String name = "";
    public Mono(String name){
        this.name = name;
    }
    @Override
    public String toString(){
        return name;
    }
}
class Momo extends Mono {
    Momo(){
        super("桃");
    }
    Momotaro bornMomotaro(){
        return new Momotaro(); //桃太郎が生まれる
    }
}
class Kibidango extends Mono {
    Kibidango(){
        super("きび団子");
    }
}
class Fukuro extends Mono {
    ArrayDeque<Mono> fukuro; 
    Fukuro(){
        super("きび団子が入った袋");
        fukuro = new ArrayDeque<Mono>();
    }
    public void add(Mono mono){
        fukuro.add(mono);
    }
    public Mono pop(){
        return fukuro.pop();
    }
    public int size(){
        return fukuro.size();
    }
}