private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
  char ch;
  ch = e.KeyChar;
  if (ch == '\r')
  {
     a[i] = Convert.ToInt32(textBox1.Text);
     i++;
     if (i < count)
     {
        textBox1.Text = "";
        textBox1.Focus();
        label1.Text = "Number " + Convert.ToString(i + 1, 10);
     }
     else
     {
        i = 0;
        label1.Text = "Number " + Convert.ToString(i + 1, 10);
        MessageBox.Show(" Please Clicked Display Button");
        Display.Enabled = true;
     }
  }
}
