import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String a = sc.next();
		String pattern1 = "[a-z]";
		Pattern p = Pattern.compile(pattern1);
		Matcher m = p.matcher(a);
		if (m.find()) {
			System.out.println("a");
		} else {
			System.out.println("A");
		}
		sc.close();
	}
} import java.util.Scanner; Scanner java.util import java.util.regex.Matcher; Matcher java.util.regex import java.util.regex.Pattern; Pattern java.util.regex public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String a = sc.next();
		String pattern1 = "[a-z]";
		Pattern p = Pattern.compile(pattern1);
		Matcher m = p.matcher(a);
		if (m.find()) {
			System.out.println("a");
		} else {
			System.out.println("A");
		}
		sc.close();
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String a = sc.next();
		String pattern1 = "[a-z]";
		Pattern p = Pattern.compile(pattern1);
		Matcher m = p.matcher(a);
		if (m.find()) {
			System.out.println("a");
		} else {
			System.out.println("A");
		}
		sc.close();
	} main {
		Scanner sc = new Scanner(System.in);
		String a = sc.next();
		String pattern1 = "[a-z]";
		Pattern p = Pattern.compile(pattern1);
		Matcher m = p.matcher(a);
		if (m.find()) {
			System.out.println("a");
		} else {
			System.out.println("A");
		}
		sc.close();
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) String a = sc.next(); a sc.next() sc.next sc String pattern1 = "[a-z]"; pattern1 "[a-z]" Pattern p = Pattern.compile(pattern1); p Pattern.compile(pattern1) Pattern.compile Pattern pattern1 Matcher m = p.matcher(a); m p.matcher(a) p.matcher p a if (m.find()) {
			System.out.println("a");
		} else {
			System.out.println("A");
		} m.find() m.find m {
			System.out.println("a");
		} System.out.println("a") System.out.println System.out System System.out "a" {
			System.out.println("A");
		} System.out.println("A") System.out.println System.out System System.out "A" sc.close() sc.close sc String[] args args public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String a = sc.next();
		String pattern1 = "[a-z]";
		Pattern p = Pattern.compile(pattern1);
		Matcher m = p.matcher(a);
		if (m.find()) {
			System.out.println("a");
		} else {
			System.out.println("A");
		}
		sc.close();
	}
} public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String a = sc.next();
		String pattern1 = "[a-z]";
		Pattern p = Pattern.compile(pattern1);
		Matcher m = p.matcher(a);
		if (m.find()) {
			System.out.println("a");
		} else {
			System.out.println("A");
		}
		sc.close();
	}
} Main
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String a = sc.next();
		String pattern1 = "[a-z]";
		Pattern p = Pattern.compile(pattern1);
		Matcher m = p.matcher(a);
		if (m.find()) {
			System.out.println("a");
		} else {
			System.out.println("A");
		}
		sc.close();
	}
}
