menampilakan huruf yang sama dari 2 inputan

Module Module1

    Sub Main()
        Dim x, y, i As Integer
        Dim a, b, tmp, t, z As String
        Console.Write("Masukkan kata Ke-1: ")
        a = Console.ReadLine()
        Console.Write("Masukkan kata Ke-2: ")
        b = Console.ReadLine()
        Console.WriteLine()
        Console.WriteLine()
        i = 1
        x = 1
        While (x <= Len(a))
            y = 1
            While (y <= Len(b))
                If Mid(a, x, 1) = Mid(b, y, 1) And i <= 1 Then
                    tmp = tmp + Mid(a, x, 1)
                    i = i + 1
                End If
                y = y + 1
            End While
            i = 1
            x = x + 1
        End While
        For x = 1 To Len(tmp)
            For y = 1 To Len(tmp) - 1
                If Mid(tmp, y, 1) > Mid(tmp, y + 1, 1) Then
                    t = Mid(tmp, y, 1)
                    Mid(tmp, y, 1) = Mid(tmp, y + 1, 1)
                    Mid(tmp, y + 1, 1) = t
                End If
            Next
        Next
        Console.Write("Huruf yang Sama : ")
        For y = 1 To Len(tmp) + 1
            If Mid(tmp, y, 1) <> Mid(tmp, y + 1, 1) Then
                Console.Write(Mid(tmp, y, 1) & ",")
            End If
        Next

        Console.WriteLine()
        Console.WriteLine()
        'Console.Write(tmp)
        Console.ReadLine()
    End Sub

End Module