import java.util.Scanner;

public class Main {
   public static void main(String[] args) {
       Scanner s = new Scanner(System.in);
       String st = s.next();
       char c = st.charAt(0);
       if(Character.isUpperCase(c)) {
           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