import java.util.Scanner;
 
public class Main {
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        String S = in.nextLine();
      String str1 = new String(S);
          if(Character.isUpperCase(str1.charAt( 0 ))){
            String T = str1.toLowerCase();
            System.out.println("A");
          }
         else {String T = str1.toUpperCase();
           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