import java.util.*;
 class Main{
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        char s=sc.nextLine().toCharArray()[0];
        boolean b=Character.isLowerCase(s);
        if(b){
            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