import java.util.Scanner;

public class Main{
	public static void main(String args[]){
    	Scanner sc = new Scanner(System.in);
      
      	String a = sc.next();
      
      	String b = a.toLowerCase();
      
      	if(a.equals(b))
          System.out.print("a");
      else 
          System.out.print("A");
    }
} import java.util.Scanner; Scanner java.util public class Main{
	public static void main(String args[]){
    	Scanner sc = new Scanner(System.in);
      
      	String a = sc.next();
      
      	String b = a.toLowerCase();
      
      	if(a.equals(b))
          System.out.print("a");
      else 
          System.out.print("A");
    }
} Main public static void main(String args[]){
    	Scanner sc = new Scanner(System.in);
      
      	String a = sc.next();
      
      	String b = a.toLowerCase();
      
      	if(a.equals(b))
          System.out.print("a");
      else 
          System.out.print("A");
    } main {
    	Scanner sc = new Scanner(System.in);
      
      	String a = sc.next();
      
      	String b = a.toLowerCase();
      
      	if(a.equals(b))
          System.out.print("a");
      else 
          System.out.print("A");
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) String a = sc.next(); a sc.next() sc.next sc String b = a.toLowerCase(); b a.toLowerCase() a.toLowerCase a if(a.equals(b))
          System.out.print("a");
      else 
          System.out.print("A"); a.equals(b) a.equals a b System.out.print("a") System.out.print System.out System System.out "a" System.out.print("A") System.out.print System.out System System.out "A" String args[] args public class Main{
	public static void main(String args[]){
    	Scanner sc = new Scanner(System.in);
      
      	String a = sc.next();
      
      	String b = a.toLowerCase();
      
      	if(a.equals(b))
          System.out.print("a");
      else 
          System.out.print("A");
    }
} public class Main{
	public static void main(String args[]){
    	Scanner sc = new Scanner(System.in);
      
      	String a = sc.next();
      
      	String b = a.toLowerCase();
      
      	if(a.equals(b))
          System.out.print("a");
      else 
          System.out.print("A");
    }
} Main
import java.util.Scanner;

public class Main{
	public static void main(String args[]){
    	Scanner sc = new Scanner(System.in);
      
      	String a = sc.next();
      
      	String b = a.toLowerCase();
      
      	if(a.equals(b))
          System.out.print("a");
      else 
          System.out.print("A");
    }
}