print（ - ）减去十进制值RightToLeft

Question

decimal abc = -123;
StringFormat drawFormat = new StringFormat();
drawFormat.FormatFlags = StringFormatFlags.DirectionRightToLeft;

graphics.DrawString(abc.ToString(), new Font("Segoe UI", 10, FontStyle.Bold), new SolidBrush(Color.Black), 100, 100, drawFormat);

返回123- 但我想要-123。