import java.util.*;
class Main {
 public static void main(String[] args) {
   Scanner scan = new Scanner(System.in);
   String str = scan.nextLine();
   if(str == str.toUpperCase()) {
   	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