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

public class Main {
	public static void main(String[] args){
		// input
		Scanner inData = new Scanner(System.in);

		String line = inData.nextLine();
		String regex = "[a-z]";
		Pattern p = Pattern.compile(regex);
		Matcher m = p.matcher(line);

		if (m.find()) {
			System.out.println("a");
		} else {
			System.out.println("A");
		}

		inData.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){
		// input
		Scanner inData = new Scanner(System.in);

		String line = inData.nextLine();
		String regex = "[a-z]";
		Pattern p = Pattern.compile(regex);
		Matcher m = p.matcher(line);

		if (m.find()) {
			System.out.println("a");
		} else {
			System.out.println("A");
		}

		inData.close();
	}
} Main public static void main(String[] args){
		// input
		Scanner inData = new Scanner(System.in);

		String line = inData.nextLine();
		String regex = "[a-z]";
		Pattern p = Pattern.compile(regex);
		Matcher m = p.matcher(line);

		if (m.find()) {
			System.out.println("a");
		} else {
			System.out.println("A");
		}

		inData.close();
	} main {
		// input
		Scanner inData = new Scanner(System.in);

		String line = inData.nextLine();
		String regex = "[a-z]";
		Pattern p = Pattern.compile(regex);
		Matcher m = p.matcher(line);

		if (m.find()) {
			System.out.println("a");
		} else {
			System.out.println("A");
		}

		inData.close();
	} Scanner inData = new Scanner(System.in); inData new Scanner(System.in) String line = inData.nextLine(); line inData.nextLine() inData.nextLine inData String regex = "[a-z]"; regex "[a-z]" Pattern p = Pattern.compile(regex); p Pattern.compile(regex) Pattern.compile Pattern regex Matcher m = p.matcher(line); m p.matcher(line) p.matcher p line 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" inData.close() inData.close inData String[] args args public class Main {
	public static void main(String[] args){
		// input
		Scanner inData = new Scanner(System.in);

		String line = inData.nextLine();
		String regex = "[a-z]";
		Pattern p = Pattern.compile(regex);
		Matcher m = p.matcher(line);

		if (m.find()) {
			System.out.println("a");
		} else {
			System.out.println("A");
		}

		inData.close();
	}
} public class Main {
	public static void main(String[] args){
		// input
		Scanner inData = new Scanner(System.in);

		String line = inData.nextLine();
		String regex = "[a-z]";
		Pattern p = Pattern.compile(regex);
		Matcher m = p.matcher(line);

		if (m.find()) {
			System.out.println("a");
		} else {
			System.out.println("A");
		}

		inData.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){
		// input
		Scanner inData = new Scanner(System.in);

		String line = inData.nextLine();
		String regex = "[a-z]";
		Pattern p = Pattern.compile(regex);
		Matcher m = p.matcher(line);

		if (m.find()) {
			System.out.println("a");
		} else {
			System.out.println("A");
		}

		inData.close();
	}
}
