import java.io.*;
import java.util.*;

public class Main{
	public static void main(String[] args){
    	Scanner s = new Scanner(System.in);
      	char c = s.next().charAt(0);
      	if (Character.isUpperCase(c)){
          	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