import java.util.Vector;

class Pt extends Object {
  float x;
  float y;
  Pt(float _x, float _y) { x = _x; y = _y; }
}
class Pt3D extends Pt {
  float z;
  Pt3D(float _x, float _y, float _z) { super(_x,_y); z = _z; }
}
/*class C extends Object {
  void f(Pt3D p1, Pt   p2) {}
  void f(Pt   p1, Pt3D p2) {}
  void g(Pt3D p1, Pt3D p2) {
    f(p1,p2);
  }
  }*/

interface I {
  Object apply(Object o);
}
class Compose implements I {
  I f;
  I g;
  public Object apply(Object o) {
    return g.apply(f.apply(o));
  }
  Compose(I _f, I _g) {f = _f; g = _g;}
}
class A1 implements I { 
  public Object apply(Object o) { return apply((Pt) o); }
  public Pt3D apply(Pt   p) { return new Pt3D(p.x, p.y, 0);}
}
class A2 implements I {
  public Object apply(Object o) { return apply((Pt3D) o); }
  public Pt  apply(Pt3D p) { return new Pt(p.x, p.y); }
}
class A3 {
  void f() {
    I copyPoint = new Compose(new A1(), new A2());
    Pt p = (Pt)copyPoint.apply(new Pt(3,4));
  }
}

class B1 {
  void f() {
  Vector  v  = new Vector(10);
  char [] a = new char[1];
  a[0] = 'h';
  v.add(0,a);
  char c = ((char[])v.elementAt(0))[0];
  // more interestingly, this is why Java encourages iterators instead of
  // passing in objects with apply methods (see above)
  }
}

interface J {
  int apply(Object env, String str);
}
class B2 {
  int f(Object env, J g) {
    String s1 = "hi";
    String s2 = "mom";
    return g.apply(env,s1) + g.apply(env,s2);
  }
}
class B3 implements J {
  public int apply(Object env, String str) {
    String otherString = (String) env;
    int len1 = otherString.length();
    int len2 = str.length();
    return len1 > len2 ? len1 : len2;
  }
  void f() {
    B2 b = new B2();
    b.f("glob",this);
    b.f(new Object(), this);
  }
}