class Nil extends Exception
{
}

class Cons extends Exception
{
  private Object x;
  private ListThunk s;
  public Cons(Object x, ListThunk s) {
    this.x = x;
    this.s = s;
  }
  public Object x() {
    return x;
  }
  public ListThunk s() {
    return s;
  }
}

interface ListThunk
{
  public void s() throws Nil, Cons;
}

interface Transform
{
  public Object f(Object x);
}

class Map implements ListThunk
{
  private Transform f;
  private ListThunk l;
  public Map(Transform f, ListThunk l) {
    this.f = f;
    this.l = l;
  }
  public void s() throws Nil, Cons {
    try {
      l.s();
    }
    catch (Nil n) {
      throw n;
    }
    catch (Cons c) {
      throw new Cons(f.f(c.x()), new Map(f, c.s()));
    }
  }
}

class Cycle implements ListThunk
{
  private Object x;
  public Cycle(Object x) {
    this.x = x;
  }
  public void s() throws Cons {
    throw new Cons(x, this);
  }
}

public class Nightmare
{
  public static void print(ListThunk l) {
    try {
      l.s();
    }
    catch (Nil n) {
    }
    catch (Cons c) {
      System.out.println(c.x());
      print(c.s());
    }
  }
  public static void main(String args[]) {
    ListThunk l = new Map(new Transform() {
      public Object f(Object x) {
        return ((String)x).toLowerCase();
      }
    }, new Cycle(args[0]));
    print(l);
  }
}