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

public class Main {

    public static void main (String [] args) throws IOException {
        BufferedReader f = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out = new PrintWriter(System.out);
        //--------------------------START CODING HERE-----------------------------
        String line =f.readLine();
        if(line.matches("[a-z]"))
            out.print("a");
        else
            {
                out.print("A");
            }

        out.close();
    }
} import java.io.*; io.* java import java.util.StringTokenizer; StringTokenizer java.util public class Main {

    public static void main (String [] args) throws IOException {
        BufferedReader f = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out = new PrintWriter(System.out);
        //--------------------------START CODING HERE-----------------------------
        String line =f.readLine();
        if(line.matches("[a-z]"))
            out.print("a");
        else
            {
                out.print("A");
            }

        out.close();
    }
} Main public static void main (String [] args) throws IOException {
        BufferedReader f = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out = new PrintWriter(System.out);
        //--------------------------START CODING HERE-----------------------------
        String line =f.readLine();
        if(line.matches("[a-z]"))
            out.print("a");
        else
            {
                out.print("A");
            }

        out.close();
    } main {
        BufferedReader f = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out = new PrintWriter(System.out);
        //--------------------------START CODING HERE-----------------------------
        String line =f.readLine();
        if(line.matches("[a-z]"))
            out.print("a");
        else
            {
                out.print("A");
            }

        out.close();
    } BufferedReader f = new BufferedReader(new InputStreamReader(System.in)); f new BufferedReader(new InputStreamReader(System.in)) PrintWriter out = new PrintWriter(System.out); out new PrintWriter(System.out) String line =f.readLine(); line f.readLine() f.readLine f if(line.matches("[a-z]"))
            out.print("a");
        else
            {
                out.print("A");
            } line.matches("[a-z]") line.matches line "[a-z]" out.print("a") out.print out "a" {
                out.print("A");
            } out.print("A") out.print out "A" out.close() out.close out String [] args args public class Main {

    public static void main (String [] args) throws IOException {
        BufferedReader f = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out = new PrintWriter(System.out);
        //--------------------------START CODING HERE-----------------------------
        String line =f.readLine();
        if(line.matches("[a-z]"))
            out.print("a");
        else
            {
                out.print("A");
            }

        out.close();
    }
} public class Main {

    public static void main (String [] args) throws IOException {
        BufferedReader f = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out = new PrintWriter(System.out);
        //--------------------------START CODING HERE-----------------------------
        String line =f.readLine();
        if(line.matches("[a-z]"))
            out.print("a");
        else
            {
                out.print("A");
            }

        out.close();
    }
} Main
import java.io.*;
import java.util.StringTokenizer;

public class Main {

    public static void main (String [] args) throws IOException {
        BufferedReader f = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out = new PrintWriter(System.out);
        //--------------------------START CODING HERE-----------------------------
        String line =f.readLine();
        if(line.matches("[a-z]"))
            out.print("a");
        else
            {
                out.print("A");
            }

        out.close();
    }
}