@NotNull
  private static String arrayToString(int @NotNull [] array) {
    int n = array.length;
    if (n == 0) return "";
    StringBuilder b = new StringBuilder(array.length * 4);
    b.append(array[0]);
    for (int i = 1; i < n; i++) b.append(',').append(' ').append(array[i]);
    return b.toString();
  }
@NotNull
  private static String arrayToString(int @NotNull [] array)