import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        char input = in.next().charAt(0);
        char output = alphabet(input);
        System.out.println(output);
    }

    // alpha = 'B' -> 'A'
    // alpha = 'z' -> 'a'
    public static char alphabet(char alpha) {
        char result = 'a';
        if (alpha >= 'A' && alpha <= 'Z') {
            result = 'A';
        } else {
            result = 'a';
        }
        return result;
    }

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

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        char input = in.next().charAt(0);
        char output = alphabet(input);
        System.out.println(output);
    }

    // alpha = 'B' -> 'A'
    // alpha = 'z' -> 'a'
    public static char alphabet(char alpha) {
        char result = 'a';
        if (alpha >= 'A' && alpha <= 'Z') {
            result = 'A';
        } else {
            result = 'a';
        }
        return result;
    }

} Main public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        char input = in.next().charAt(0);
        char output = alphabet(input);
        System.out.println(output);
    } main {
        Scanner in = new Scanner(System.in);
        char input = in.next().charAt(0);
        char output = alphabet(input);
        System.out.println(output);
    } Scanner in = new Scanner(System.in); in new Scanner(System.in) char input = in.next().charAt(0); input in.next().charAt(0) in.next().charAt in.next() in.next in 0 char output = alphabet(input); output alphabet(input) alphabet input System.out.println(output) System.out.println System.out System System.out output String[] args args // alpha = 'B' -> 'A'
    // alpha = 'z' -> 'a'
    public static char alphabet(char alpha) {
        char result = 'a';
        if (alpha >= 'A' && alpha <= 'Z') {
            result = 'A';
        } else {
            result = 'a';
        }
        return result;
    } alphabet {
        char result = 'a';
        if (alpha >= 'A' && alpha <= 'Z') {
            result = 'A';
        } else {
            result = 'a';
        }
        return result;
    } char result = 'a'; result 'a' if (alpha >= 'A' && alpha <= 'Z') {
            result = 'A';
        } else {
            result = 'a';
        } alpha >= 'A' && alpha <= 'Z' alpha >= 'A' alpha 'A' alpha <= 'Z' alpha 'Z' {
            result = 'A';
        } result = 'A' result 'A' {
            result = 'a';
        } result = 'a' result 'a' return result; result char alpha alpha public class Main {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        char input = in.next().charAt(0);
        char output = alphabet(input);
        System.out.println(output);
    }

    // alpha = 'B' -> 'A'
    // alpha = 'z' -> 'a'
    public static char alphabet(char alpha) {
        char result = 'a';
        if (alpha >= 'A' && alpha <= 'Z') {
            result = 'A';
        } else {
            result = 'a';
        }
        return result;
    }

} public class Main {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        char input = in.next().charAt(0);
        char output = alphabet(input);
        System.out.println(output);
    }

    // alpha = 'B' -> 'A'
    // alpha = 'z' -> 'a'
    public static char alphabet(char alpha) {
        char result = 'a';
        if (alpha >= 'A' && alpha <= 'Z') {
            result = 'A';
        } else {
            result = 'a';
        }
        return result;
    }

} Main
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        char input = in.next().charAt(0);
        char output = alphabet(input);
        System.out.println(output);
    }

    // alpha = 'B' -> 'A'
    // alpha = 'z' -> 'a'
    public static char alphabet(char alpha) {
        char result = 'a';
        if (alpha >= 'A' && alpha <= 'Z') {
            result = 'A';
        } else {
            result = 'a';
        }
        return result;
    }

}
