@Override
    public IntSet read(final @NotNull DataInput in) throws IOException {
      final IntSet result = new IntOpenHashSet();
      final DataInputStream stream = (DataInputStream)in;
      while (stream.available() > 0) {
        final int elem = DataInputOutputUtil.readINT(in);
        if (elem < 0) {
          result.remove(-elem);
        }
        else if (elem > 0) {
          result.add(elem);
        }
      }
      return result;
    }
@Override
    public IntSet read(final @NotNull DataInput in)