import java.util.*;
import java.io.*;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(new BufferedReader(new InputStreamReader(System.in)));
		String s = sc.next();
		if (s.toUpperCase() == s) {
			System.out.println('A');
		} else {
			System.out.println('a');
		}
	}
} import java.util.*; util.* java import java.io.*; io.* java public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(new BufferedReader(new InputStreamReader(System.in)));
		String s = sc.next();
		if (s.toUpperCase() == s) {
			System.out.println('A');
		} else {
			System.out.println('a');
		}
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(new BufferedReader(new InputStreamReader(System.in)));
		String s = sc.next();
		if (s.toUpperCase() == s) {
			System.out.println('A');
		} else {
			System.out.println('a');
		}
	} main {
		Scanner sc = new Scanner(new BufferedReader(new InputStreamReader(System.in)));
		String s = sc.next();
		if (s.toUpperCase() == s) {
			System.out.println('A');
		} else {
			System.out.println('a');
		}
	} Scanner sc = new Scanner(new BufferedReader(new InputStreamReader(System.in))); sc new Scanner(new BufferedReader(new InputStreamReader(System.in))) String s = sc.next(); s sc.next() sc.next sc if (s.toUpperCase() == s) {
			System.out.println('A');
		} else {
			System.out.println('a');
		} s.toUpperCase() == s s.toUpperCase() s.toUpperCase s s {
			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 public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(new BufferedReader(new InputStreamReader(System.in)));
		String s = sc.next();
		if (s.toUpperCase() == s) {
			System.out.println('A');
		} else {
			System.out.println('a');
		}
	}
} public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(new BufferedReader(new InputStreamReader(System.in)));
		String s = sc.next();
		if (s.toUpperCase() == s) {
			System.out.println('A');
		} else {
			System.out.println('a');
		}
	}
} Main
import java.util.*;
import java.io.*;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(new BufferedReader(new InputStreamReader(System.in)));
		String s = sc.next();
		if (s.toUpperCase() == s) {
			System.out.println('A');
		} else {
			System.out.println('a');
		}
	}
}