import java.lang.Character;
import java.util.Scanner;

public class Main {

    static void solve(String s ) {
        char bruh = s.charAt(0);
        if(Character.isUpperCase(bruh)){
            System.out.println("A");
        } else System.out.println("a");

    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
            String input = in.next();
            solve(input);

    }
}
/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