import java.util.Scanner;
public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        String s = sc.next();
        char a = s.charAt(0);
        char aa = 'a';
        char zz = 'z';
        int nu = aa;
        int zu = zz;
        int che = a;
        if(nu <= che && che <= zu){
            System.out.println("a");
        }else{
            System.out.println("A");
        }
        sc.close();
    }
}
/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