private void dataGridView1_RowPostPaint(object sender, DataGridViewRowPostPaintEventArgs e)
{
Rectangle rectangle = new Rectangle(e.RowBounds.Location.X, e.RowBounds.Location.Y, dataGridView1.RowHeadersWidth, e.RowBounds.Height);
TextRenderer.DrawText(e.Graphics, (e.RowIndex + 1).ToString(), dataGridView1.RowHeadersDefaultCellStyle.Font, rectangle, dataGridView1.RowHeadersDefaultCellStyle.ForeColor, TextFormatFlags.VerticalCenter | TextFormatFlags.Right);
}