Sub otuhu()
Dim ColNum As Long
ColNum = Range("T1").End(xlToRight).Column + 1
If Range("T1") = "" Then
Columns("C:C").Copy Columns(20)
ElseIf Range("U1") = "" Then
Columns("C:C").Copy Columns(21)
Else
Columns("C:C").Copy Columns(ColNum)
End If
End Sub