import java.util.Iterator;
import java.util.NoSuchElementException;

class FifoListe<T> implements Iterable<T> {

    private Node hode;
    private Node hale;
  
    private class Node {
      Node neste;
      T ting;
  
      Node(T ting) {
        this.ting = ting;
      }
    }

    void skriv_rek_sist() {
      // implementer den rekursive funksjonen
    }

    void skriv_rek_forst() {
      // implementer den rekursive funksjonen
    }

    int antNoder() {
      // implementer den rekursive funksjonen
      return 0;
    }
  
    public int storrelse() {
      int teller = 0;
      for (Node tmp = hode; tmp != null; tmp = tmp.neste) {
        teller++;
      }
      return teller;
    }
  
    public boolean erTom() {
      return hode == null;
    }
  
    public void leggTil(T t) {
      Node nyNode = new Node(t);
      if (erTom()) {
        hode = nyNode;
      }
      else {
        hale.neste = nyNode;
      }
      hale = nyNode;
    }
  
    public void fjernAlt() {
      hode = null;
      hale = null;
    }
  
    public T pop() {
      Node returnode = hode;
      hode = hode.neste;
      return returnode.ting;
    }
  
    public void skrivUtListe() {
      Node tmp = hode;
      System.out.println("[");
      while (tmp != null) {
        System.out.println("\t" + tmp.ting);
        tmp = tmp.neste;
      }
      System.out.println("]");
    }
  
    public Iterator<T> iterator() {
      return new FIFOIterator();
    }
  
    private class FIFOIterator implements Iterator<T> {
  
      Node denne = hode;
  
      @Override
      public boolean hasNext() {
        return denne != null;
      }
  
      @Override
      public T next() {
        if (denne == null) throw new NoSuchElementException("next");
        Node tmp = denne;
        denne = denne.neste;
        return tmp.ting;
      }
    }
}