import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
    
    // 文字列の入力
    String s = sc.next();
		// 出力
    String ans = s.matches("[A-Z]") ? "A":"a";
    System.out.println(ans);
	}
} import java.util.*; util.* java public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
    
    // 文字列の入力
    String s = sc.next();
		// 出力
    String ans = s.matches("[A-Z]") ? "A":"a";
    System.out.println(ans);
	}
} Main public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
    
    // 文字列の入力
    String s = sc.next();
		// 出力
    String ans = s.matches("[A-Z]") ? "A":"a";
    System.out.println(ans);
	} main {
		Scanner sc = new Scanner(System.in);
    
    // 文字列の入力
    String s = sc.next();
		// 出力
    String ans = s.matches("[A-Z]") ? "A":"a";
    System.out.println(ans);
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) String s = sc.next(); s sc.next() sc.next sc String ans = s.matches("[A-Z]") ? "A":"a"; ans s.matches("[A-Z]") ? "A":"a" s.matches("[A-Z]") s.matches s "[A-Z]" "A" "a" System.out.println(ans) System.out.println System.out System System.out ans String[] args args public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
    
    // 文字列の入力
    String s = sc.next();
		// 出力
    String ans = s.matches("[A-Z]") ? "A":"a";
    System.out.println(ans);
	}
} public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
    
    // 文字列の入力
    String s = sc.next();
		// 出力
    String ans = s.matches("[A-Z]") ? "A":"a";
    System.out.println(ans);
	}
} Main
import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
    
    // 文字列の入力
    String s = sc.next();
		// 出力
    String ans = s.matches("[A-Z]") ? "A":"a";
    System.out.println(ans);
	}
}