import java.util.*;

/** Extra: Pinon toteutus LinkedList -luokkaan pohjautuen */

class Pino extends LinkedList  {
  public Pino() { super(); }

  // Lisäys
  public boolean push(Object o) {
    return super.add(o);
  }

  // Poisto
  public Object pop() {
    if (super.size() >= 1)
      return super.remove(super.size()-1);
     else
       return null;
  }

}


public class StackTesti {
  public static void main(String args[]) {
    Pino pino = new Pino();
    pino.push("Pekka");
    pino.push("Maija");
    System.out.println(pino.pop());
    pino.push("Jaana");
    System.out.println("pinossa alkiota: " + pino.size());
    System.out.println(pino.pop());
    System.out.println(pino.pop());
    System.out.println(pino.pop());

  }
}