Display row numbers in a DataGridView

{
 if (DataGridView1.Rows.Count > 0) {
  for (ulong r = 0; r <= DataGridView1.Rows.Count - 1; r++) {
   DataGridView1.Rows(r).HeaderCell.Value = (r + 1).ToString;
  }
 }
 DataGridView1.AutoResizeRowHeadersWidth(DataGridViewRowHeadersWidthSizeMode.AutoSizeToAllHeaders);
}