//package atcoder;
 
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.*;
//import java.math.BigDecimal;
 
public class Main {
	public static void main(String [] args) {
	    String x;
		Scanner sc = new Scanner(System.in);
		x=sc.next();
		//char char型の値 = 変数.next().charAt(取得したい位置);
		
		if(x.charAt(0)=='A'||x.charAt(0)=='B'||x.charAt(0)=='C'||x.charAt(0)=='D'||x.charAt(0)=='E'||x.charAt(0)=='F'||x.charAt(0)=='G'||x.charAt(0)=='H'||x.charAt(0)=='I'||x.charAt(0)=='J'||x.charAt(0)=='K'||x.charAt(0)=='L'||x.charAt(0)=='M'||x.charAt(0)=='N'||x.charAt(0)=='O'||x.charAt(0)=='P'||x.charAt(0)=='Q'||x.charAt(0)=='R'||x.charAt(0)=='S'||x.charAt(0)=='T'||x.charAt(0)=='U'||x.charAt(0)=='V'||x.charAt(0)=='W'||x.charAt(0)=='Y'||x.charAt(0)=='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