//package beg_171;
import java.util.*;
import java.lang.*;
public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner s = new Scanner(System.in);
		char a = s.nextLine().charAt(0);
		
		boolean b = Character.isUpperCase(a);
		
		if (b) {
			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