import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.regex.*;

public class Main {


    public static void main(String[] args) throws IOException {
    
    	Scanner scan = new Scanner(System.in);
   
    	char [] ch = scan.next().toCharArray();
    	
    	if(Character.isLowerCase(ch[0])) 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