interface Xformer { Object xform(Object o); }
 
abstract class List {
  abstract List map(Xformer x);
}
 
class Empty extends List {
  Empty() { }
  List map(Xformer x) { return new Empty (); }
}
 
class Cons extends List {
  Object first; List rest;
  Cons(Object first, List rest) {
   this.first = first; this.rest = rest;
  }
  List map(Xformer x) {
    return new Cons(x.xform(this.first),
                    this.rest.map(x));
  }
}

class Append implements Xformer {
   String s;
   Append(String s) { this.s = s;}
   Object xform(Object o) {
     return ((String)o).concat(s);
   }
}

class Upcase implements Xformer {
  Upcase() { }
  Object xform(Object o) { 
    return ((String)o).toUpperCase();
  }
}



class Fish {
  double weight;
  Fish(double weight) {
    this.weight = weight;
  }
  double getWeight() {
    return this.weight;
  }
  void feed(double n) {
    this.weight = this.weight + n;
  }
}

class Aq {
  List fishes;
  int count;
  Aq() {
    this.fishes = new Empty();
    this.count = 0;
  }
  void add(Fish f) {
    this.fishes = new Cons(f, this.fishes);
    this.count = this.count + 1;
  }
  void feedAll(int n) {
    this.fishes.map(new Feeder(n));
  }
}

class Feeder implements Xformer {
  int n;
  Feeder(int n) { this.n = n; }
  Object xform(Object o) { 
    ((Fish)o).feed(this.n);
    return this; // result will be ignored, anyway
  }
}

class ColorFish extends Fish {
  String color;
  ColorFish(double weight, String color) {
    super(weight);
    this.color = color;
  }
}