import java.util.Scanner;

class Main{
	public static void main(String args[]){
		Scanner scan = new Scanner(System.in);
		String N = scan.next();
		scan.close();
		String A = "ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ";
		String a = "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz";
		if(A.contains(N)) {
			System.out.println("A");
		}else if(a.contains(N)){
			System.out.println("a");
		}
	}

} import java.util.Scanner; Scanner java.util class Main{
	public static void main(String args[]){
		Scanner scan = new Scanner(System.in);
		String N = scan.next();
		scan.close();
		String A = "ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ";
		String a = "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz";
		if(A.contains(N)) {
			System.out.println("A");
		}else if(a.contains(N)){
			System.out.println("a");
		}
	}

} Main public static void main(String args[]){
		Scanner scan = new Scanner(System.in);
		String N = scan.next();
		scan.close();
		String A = "ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ";
		String a = "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz";
		if(A.contains(N)) {
			System.out.println("A");
		}else if(a.contains(N)){
			System.out.println("a");
		}
	} main {
		Scanner scan = new Scanner(System.in);
		String N = scan.next();
		scan.close();
		String A = "ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ";
		String a = "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz";
		if(A.contains(N)) {
			System.out.println("A");
		}else if(a.contains(N)){
			System.out.println("a");
		}
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) String N = scan.next(); N scan.next() scan.next scan scan.close() scan.close scan String A = "ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ"; A "ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ" String a = "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz"; a "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz" if(A.contains(N)) {
			System.out.println("A");
		}else if(a.contains(N)){
			System.out.println("a");
		} A.contains(N) A.contains A N {
			System.out.println("A");
		} System.out.println("A") System.out.println System.out System System.out "A" if(a.contains(N)){
			System.out.println("a");
		} a.contains(N) a.contains a N {
			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 scan = new Scanner(System.in);
		String N = scan.next();
		scan.close();
		String A = "ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ";
		String a = "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz";
		if(A.contains(N)) {
			System.out.println("A");
		}else if(a.contains(N)){
			System.out.println("a");
		}
	}

}