import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
			Scanner s= new Scanner(System.in);
		  char s1= s.next().charAt(0);
		  
		  if(s1 >='A' && s1 <= 'Z')
		    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