import java.util.Scanner;

class Main {
	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		String a = sc.next();
		String aa = "abcdefghijklmnopqrstuvwxyz";
		if(aa.indexOf(a) < 0) {
			System.out.println("A");
		} else {
			System.out.println("a");
		}



	}
} import java.util.Scanner; Scanner java.util class Main {
	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		String a = sc.next();
		String aa = "abcdefghijklmnopqrstuvwxyz";
		if(aa.indexOf(a) < 0) {
			System.out.println("A");
		} else {
			System.out.println("a");
		}



	}
} Main public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		String a = sc.next();
		String aa = "abcdefghijklmnopqrstuvwxyz";
		if(aa.indexOf(a) < 0) {
			System.out.println("A");
		} else {
			System.out.println("a");
		}



	} main {

		Scanner sc = new Scanner(System.in);

		String a = sc.next();
		String aa = "abcdefghijklmnopqrstuvwxyz";
		if(aa.indexOf(a) < 0) {
			System.out.println("A");
		} else {
			System.out.println("a");
		}



	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) String a = sc.next(); a sc.next() sc.next sc String aa = "abcdefghijklmnopqrstuvwxyz"; aa "abcdefghijklmnopqrstuvwxyz" if(aa.indexOf(a) < 0) {
			System.out.println("A");
		} else {
			System.out.println("a");
		} aa.indexOf(a) < 0 aa.indexOf(a) aa.indexOf aa a 0 {
			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" String[] args args
import java.util.Scanner;

class Main {
	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		String a = sc.next();
		String aa = "abcdefghijklmnopqrstuvwxyz";
		if(aa.indexOf(a) < 0) {
			System.out.println("A");
		} else {
			System.out.println("a");
		}



	}
}
