import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		String x = scan.next();
		if(x.matches("^[a-z]*$"))System.out.println('a');
		else if(x.matches("^[A-Z]*$")) System.out.println('A');
		scan.close();
	}

} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		String x = scan.next();
		if(x.matches("^[a-z]*$"))System.out.println('a');
		else if(x.matches("^[A-Z]*$")) System.out.println('A');
		scan.close();
	}

} Main public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		String x = scan.next();
		if(x.matches("^[a-z]*$"))System.out.println('a');
		else if(x.matches("^[A-Z]*$")) System.out.println('A');
		scan.close();
	} main {
		Scanner scan = new Scanner(System.in);
		String x = scan.next();
		if(x.matches("^[a-z]*$"))System.out.println('a');
		else if(x.matches("^[A-Z]*$")) System.out.println('A');
		scan.close();
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) String x = scan.next(); x scan.next() scan.next scan if(x.matches("^[a-z]*$"))System.out.println('a');
		else if(x.matches("^[A-Z]*$")) System.out.println('A'); x.matches("^[a-z]*$") x.matches x "^[a-z]*$" System.out.println('a') System.out.println System.out System System.out 'a' if(x.matches("^[A-Z]*$")) System.out.println('A'); x.matches("^[A-Z]*$") x.matches x "^[A-Z]*$" System.out.println('A') System.out.println System.out System System.out 'A' scan.close() scan.close scan String[] args args public class Main {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		String x = scan.next();
		if(x.matches("^[a-z]*$"))System.out.println('a');
		else if(x.matches("^[A-Z]*$")) System.out.println('A');
		scan.close();
	}

} public class Main {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		String x = scan.next();
		if(x.matches("^[a-z]*$"))System.out.println('a');
		else if(x.matches("^[A-Z]*$")) System.out.println('A');
		scan.close();
	}

} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		String x = scan.next();
		if(x.matches("^[a-z]*$"))System.out.println('a');
		else if(x.matches("^[A-Z]*$")) System.out.println('A');
		scan.close();
	}

}
