try
            {
                ltbList.Items.Clear();
                int[] iArrNum = iArrUs(int.Parse(cbNum.SelectedItem.ToString()));
                for (int i = 0; i < iArrNum.Length; i++)
                {
                    ltbList.Items.Add(iArrNum[i].ToString());
                }
            }
            catch (Exception ex)
            {

                MessageBox.Show(ex.ToString());
            }