Sub Main()
Dim word As String = "Привет"
Dim count As Integer = 0
Dim vowels As String = "аеёиоуыэюяАЕЁИОУЫЭЮЯ"
For Each ch As Char In word
If vowels.Contains(ch) Then
count += 1
End If
Next
Console.WriteLine("Количество гласных букв: {0}", count)
End Sub