import java.io.*;

public class Main {
    public static void main(String[] args) throws Exception {
        try{
            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
            
            String S = br.readLine();
            
            if(S.matches("[A-Z]")){
                System.out.println("A");
            }else{
                System.out.println("a");
            }
            
        }catch(Exception e){
            System.out.println(e);
        }
    }
} import java.io.*; io.* java public class Main {
    public static void main(String[] args) throws Exception {
        try{
            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
            
            String S = br.readLine();
            
            if(S.matches("[A-Z]")){
                System.out.println("A");
            }else{
                System.out.println("a");
            }
            
        }catch(Exception e){
            System.out.println(e);
        }
    }
} Main public static void main(String[] args) throws Exception {
        try{
            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
            
            String S = br.readLine();
            
            if(S.matches("[A-Z]")){
                System.out.println("A");
            }else{
                System.out.println("a");
            }
            
        }catch(Exception e){
            System.out.println(e);
        }
    } main {
        try{
            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
            
            String S = br.readLine();
            
            if(S.matches("[A-Z]")){
                System.out.println("A");
            }else{
                System.out.println("a");
            }
            
        }catch(Exception e){
            System.out.println(e);
        }
    } try{
            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
            
            String S = br.readLine();
            
            if(S.matches("[A-Z]")){
                System.out.println("A");
            }else{
                System.out.println("a");
            }
            
        }catch(Exception e){
            System.out.println(e);
        } catch(Exception e){
            System.out.println(e);
        } Exception e {
            System.out.println(e);
        } System.out.println(e) System.out.println System.out System System.out e {
            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
            
            String S = br.readLine();
            
            if(S.matches("[A-Z]")){
                System.out.println("A");
            }else{
                System.out.println("a");
            }
            
        } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) String S = br.readLine(); S br.readLine() br.readLine br if(S.matches("[A-Z]")){
                System.out.println("A");
            }else{
                System.out.println("a");
            } S.matches("[A-Z]") S.matches S "[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" String[] args args public class Main {
    public static void main(String[] args) throws Exception {
        try{
            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
            
            String S = br.readLine();
            
            if(S.matches("[A-Z]")){
                System.out.println("A");
            }else{
                System.out.println("a");
            }
            
        }catch(Exception e){
            System.out.println(e);
        }
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        try{
            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
            
            String S = br.readLine();
            
            if(S.matches("[A-Z]")){
                System.out.println("A");
            }else{
                System.out.println("a");
            }
            
        }catch(Exception e){
            System.out.println(e);
        }
    }
} Main
import java.io.*;

public class Main {
    public static void main(String[] args) throws Exception {
        try{
            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
            
            String S = br.readLine();
            
            if(S.matches("[A-Z]")){
                System.out.println("A");
            }else{
                System.out.println("a");
            }
            
        }catch(Exception e){
            System.out.println(e);
        }
    }
}