Imports System
Imports System.Text.RegularExpressions

Module Program
    Sub Main(args As String())

        Dim sInput As String = Console.ReadLine()
        Dim rgx As New Regex("[A-Z]")


        If rgx.IsMatch(sInput) Then
            Console.WriteLine("A")
        Else
            Console.WriteLine("a")
        End If

    End Sub
End Module
