import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
      Scanner scanner = new Scanner(System.in);
      String a = scanner.nextLine();
      
      for(int m=0;m<a.length();m++) {
        char aa = a.charAt(m);
        if(Character.isLowerCase(aa) == true) {
          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