import java.util.*;

public class Main {
	Scanner sc = new Scanner(System.in);
	final int MOD = 998244353;
	final int MAX = Integer.MAX_VALUE;
	final long LMAX = Long.MAX_VALUE;
	long inf = LMAX / 2 - MAX;

	void doIt() {
		char a = sc.next().charAt(0);
		if('A' <= a && a <= 'Z') {
			System.out.println('A');
		}
		else {
			System.out.println('a');
		}

	}

	public static void main(String[] args) {
		new Main().doIt();
	}
} import java.util.*; util.* java public class Main {
	Scanner sc = new Scanner(System.in);
	final int MOD = 998244353;
	final int MAX = Integer.MAX_VALUE;
	final long LMAX = Long.MAX_VALUE;
	long inf = LMAX / 2 - MAX;

	void doIt() {
		char a = sc.next().charAt(0);
		if('A' <= a && a <= 'Z') {
			System.out.println('A');
		}
		else {
			System.out.println('a');
		}

	}

	public static void main(String[] args) {
		new Main().doIt();
	}
} Main Scanner sc = new Scanner(System.in); sc new Scanner(System.in) final int MOD = 998244353; MOD 998244353 final int MAX = Integer.MAX_VALUE; MAX Integer.MAX_VALUE Integer Integer.MAX_VALUE final long LMAX = Long.MAX_VALUE; LMAX Long.MAX_VALUE Long Long.MAX_VALUE long inf = LMAX / 2 - MAX; inf LMAX / 2 - MAX LMAX / 2 LMAX 2 MAX void doIt() {
		char a = sc.next().charAt(0);
		if('A' <= a && a <= 'Z') {
			System.out.println('A');
		}
		else {
			System.out.println('a');
		}

	} doIt {
		char a = sc.next().charAt(0);
		if('A' <= a && a <= 'Z') {
			System.out.println('A');
		}
		else {
			System.out.println('a');
		}

	} char a = sc.next().charAt(0); a sc.next().charAt(0) sc.next().charAt sc.next() sc.next sc 0 if('A' <= a && a <= 'Z') {
			System.out.println('A');
		}
		else {
			System.out.println('a');
		} 'A' <= a && a <= 'Z' 'A' <= a 'A' a a <= 'Z' a 'Z' {
			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' public static void main(String[] args) {
		new Main().doIt();
	} main {
		new Main().doIt();
	} new Main().doIt() new Main().doIt new Main() String[] args args public class Main {
	Scanner sc = new Scanner(System.in);
	final int MOD = 998244353;
	final int MAX = Integer.MAX_VALUE;
	final long LMAX = Long.MAX_VALUE;
	long inf = LMAX / 2 - MAX;

	void doIt() {
		char a = sc.next().charAt(0);
		if('A' <= a && a <= 'Z') {
			System.out.println('A');
		}
		else {
			System.out.println('a');
		}

	}

	public static void main(String[] args) {
		new Main().doIt();
	}
} public class Main {
	Scanner sc = new Scanner(System.in);
	final int MOD = 998244353;
	final int MAX = Integer.MAX_VALUE;
	final long LMAX = Long.MAX_VALUE;
	long inf = LMAX / 2 - MAX;

	void doIt() {
		char a = sc.next().charAt(0);
		if('A' <= a && a <= 'Z') {
			System.out.println('A');
		}
		else {
			System.out.println('a');
		}

	}

	public static void main(String[] args) {
		new Main().doIt();
	}
} Main
import java.util.*;

public class Main {
	Scanner sc = new Scanner(System.in);
	final int MOD = 998244353;
	final int MAX = Integer.MAX_VALUE;
	final long LMAX = Long.MAX_VALUE;
	long inf = LMAX / 2 - MAX;

	void doIt() {
		char a = sc.next().charAt(0);
		if('A' <= a && a <= 'Z') {
			System.out.println('A');
		}
		else {
			System.out.println('a');
		}

	}

	public static void main(String[] args) {
		new Main().doIt();
	}
}
