Imports System
Class Program
Private Shared Function RemoveNonCommonLetters(ByVal word1 As String, ByVal word2 As String) As String
Dim result As String = ""
For Each c As Char In word1
If word2.Contains(c) Then
result += c
End If
Next
Return result
End Function
Public Shared Sub Main()
Dim word1 As String = "forest"
Dim word2 As String = "tor"
Dim result As String = RemoveNonCommonLetters(word1, word2)
Console.WriteLine(result)
End Sub
End Class
' run:
'
' ort
'