import java.util.Scanner;

public class Main{
	public static void main(String args[]){
      Scanner scan = new Scanner(System.in);
      char a = scan.next().charAt(0);
      System.out.println(Character.isUpperCase(a) ? 'A' : '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