import java.util.Scanner;

public class Main {
    public static void main(String[] args)
    {
        Scanner scanner = new Scanner(System.in);
        String uppercase = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        String lowercase = "abcdefghijklmnopqrstuvwxyz";

        String alpha = scanner.nextLine();

        if(uppercase.contains(alpha))
            System.out.println("A");
        else
            System.out.println("a");
    }
}

/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz