test.java

import java.util.Scanner;

public class test {
  public static void main(String[] args) {
    Scanner scan = new Scanner(System.in);
    Either<Integer, String> x;
    if (scan.hasNextInt()) {
      x = Either.l(scan.nextInt());
    } else {
      x = Either.r(scan.nextLine());
    }
    String message = x.apply(new Cases<Integer, String, String>() {
      @Override
      public String l(Integer n) {
        StringBuilder result = new StringBuilder();
        for (int i = 0; i < n; i++) {
          result.append("moo");
          if (i < n && n > 1) {
            result.append(" ");
          }
        }
        return result.toString();
      }
      @Override
      public String r(String msg) {
        return "No cows because: " + msg;
      }
    });
    System.out.println(message);
  }
}

interface Cases<L, R, V> {
  public V l(L l);
  public V r(R r);
}

class Either<L, R> {
  private boolean hasL = false;
  private boolean hasR = false;
  private L l;
  private R r;
  private Either(L l, R r, boolean hasL, boolean hasR) {
    this.l = l;
    this.r = r;
    this.hasL = hasL;
    this.hasR = hasR;
  }
  public <V> V apply(Cases<L, R, V> f) {
    if (hasL) {
      return f.l(l);
    } else {
      return f.r(r);
    }
  }
  public static <L, R> Either<L, R> l(L l) {
    return new Either<L, R>(l, null, true, false);
  }
  public static <L, R> Either<L, R> r(R r) {
    return new Either<L, R>(null, r, false, true);
  }
}