Sub test()
Dim Coll As New Collection
Dim i&, j%
For j = 1 To 2
For i = 3 To Cells(65536, j).End(xlUp).Row
On Error Resume Next
Coll.Add Cells(i, j).Value, CStr(Cells(i, j).Value)
On Error GoTo 0
Next i
Next j
For i = 1 To Coll.Count
Cells(i + 2, 3).Value = Coll(i)
Next i
Range("C3:C" & Range("C65536").End(xlUp).Row).Sort Key1:=Range("C3"), Order1:=xlAscending
End Sub