import java.util.*;
public class Main {
    public static void main(String[] args){
    
    Scanner sc = new Scanner(System.in);
        String S = sc.next();
        char[]ss = S.toCharArray();
        
        if(ss[0]-0<91){
            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