import java.util.Scanner;

class Main {
    public static void main(String[] args){
        Scanner stdIn = new Scanner(System.in);

        String a = stdIn.next();

        //文字列を小文字に
        if(a.toLowerCase() == a){
            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