Sub test()
Dim alldada As Variant
Dim r As Integer
Dim c As Integer
Dim i As Integer
i = 1
alldada = ActiveSheet.UsedRange
For c = 2 To UBound(alldada, 2)
For r = 2 To UBound(alldada, 2)
If alldada(c, 1) = alldada(r, 2) Then
Exit For
End If
If r = UBound(alldada, 2) Then
i = i + 1
Cells(i, 3) = alldada(c, 1)
End If
Next
Next
End Sub