static betterCIComparator_C betterCIComparator_instance;

static betterCIComparator_C betterCIComparator() {
  if (betterCIComparator_instance == null)
    betterCIComparator_instance = new betterCIComparator_C;
  ret betterCIComparator_instance;
}

final sclass betterCIComparator_C implements Comparator<S> {
  public int compare(S s1, S s2) {
    if (s1 == null) ret s2 == null ? 0 : -1;
    if (s2 == null) ret 1;
  
    int n1 = s1.length();
    int n2 = s2.length();
    int min = Math.min(n1, n2);
    for (int i = 0; i < min; i++) {
        char c1 = s1.charAt(i);
        char c2 = s2.charAt(i);
        if (c1 != c2) {
            c1 = Character.toUpperCase(c1);
            c2 = Character.toUpperCase(c2);
            if (c1 != c2) {
                c1 = Character.toLowerCase(c1);
                c2 = Character.toLowerCase(c2);
                if (c1 != c2) {
                    // No overflow because of numeric promotion
                    return c1 - c2;
                }
            }
        }
    }
    return n1 - n2;
  }
}