import java.util.*;

public class Main{

    public static void main(String args[]){

        Scanner sc = new Scanner(System.in);
        String str = "";

        str = sc.next();

        if (Character.isUpperCase( str.charAt( 0 ))){
            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