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

public class Main
{
    public static void main(String [] args) throws Exception
    {
        Scanner sc = new Scanner(System.in) ;
        PrintWriter out = new PrintWriter(System.out) ;
        char c = sc.next().charAt(0);
        if(Character.isUpperCase(c))
            out.println('A');
        else
            out.println('a');

        out.flush();
        out.close();
    }
    static class Scanner
    {
        BufferedReader br ;
        StringTokenizer st ;

        Scanner(InputStream in)
        {
            br = new BufferedReader(new InputStreamReader(in)) ;
        }

        String next() throws Exception
        {
            while(st == null || !st.hasMoreTokens())
                st = new StringTokenizer(br.readLine()) ;
            return st.nextToken() ;
        }

        int nextInt() throws Exception { return Integer.parseInt(next()) ; }

        long nextLong() throws Exception {return Long.parseLong(next()) ; }
    }
} import java.util.*; util.* java import java.io.* ; io.* java public class Main
{
    public static void main(String [] args) throws Exception
    {
        Scanner sc = new Scanner(System.in) ;
        PrintWriter out = new PrintWriter(System.out) ;
        char c = sc.next().charAt(0);
        if(Character.isUpperCase(c))
            out.println('A');
        else
            out.println('a');

        out.flush();
        out.close();
    }
    static class Scanner
    {
        BufferedReader br ;
        StringTokenizer st ;

        Scanner(InputStream in)
        {
            br = new BufferedReader(new InputStreamReader(in)) ;
        }

        String next() throws Exception
        {
            while(st == null || !st.hasMoreTokens())
                st = new StringTokenizer(br.readLine()) ;
            return st.nextToken() ;
        }

        int nextInt() throws Exception { return Integer.parseInt(next()) ; }

        long nextLong() throws Exception {return Long.parseLong(next()) ; }
    }
} Main public static void main(String [] args) throws Exception
    {
        Scanner sc = new Scanner(System.in) ;
        PrintWriter out = new PrintWriter(System.out) ;
        char c = sc.next().charAt(0);
        if(Character.isUpperCase(c))
            out.println('A');
        else
            out.println('a');

        out.flush();
        out.close();
    } main {
        Scanner sc = new Scanner(System.in) ;
        PrintWriter out = new PrintWriter(System.out) ;
        char c = sc.next().charAt(0);
        if(Character.isUpperCase(c))
            out.println('A');
        else
            out.println('a');

        out.flush();
        out.close();
    } Scanner sc = new Scanner(System.in) ; sc new Scanner(System.in) PrintWriter out = new PrintWriter(System.out) ; out new PrintWriter(System.out) char c = sc.next().charAt(0); c sc.next().charAt(0) sc.next().charAt sc.next() sc.next sc 0 if(Character.isUpperCase(c))
            out.println('A');
        else
            out.println('a'); Character.isUpperCase(c) Character.isUpperCase Character c out.println('A') out.println out 'A' out.println('a') out.println out 'a' out.flush() out.flush out out.close() out.close out String [] args args static class Scanner
    {
        BufferedReader br ;
        StringTokenizer st ;

        Scanner(InputStream in)
        {
            br = new BufferedReader(new InputStreamReader(in)) ;
        }

        String next() throws Exception
        {
            while(st == null || !st.hasMoreTokens())
                st = new StringTokenizer(br.readLine()) ;
            return st.nextToken() ;
        }

        int nextInt() throws Exception { return Integer.parseInt(next()) ; }

        long nextLong() throws Exception {return Long.parseLong(next()) ; }
    } Scanner BufferedReader br ; br StringTokenizer st ; st Scanner(InputStream in)
        {
            br = new BufferedReader(new InputStreamReader(in)) ;
        } Scanner {
            br = new BufferedReader(new InputStreamReader(in)) ;
        } br = new BufferedReader(new InputStreamReader(in)) br new BufferedReader(new InputStreamReader(in)) InputStream in in String next() throws Exception
        {
            while(st == null || !st.hasMoreTokens())
                st = new StringTokenizer(br.readLine()) ;
            return st.nextToken() ;
        } next {
            while(st == null || !st.hasMoreTokens())
                st = new StringTokenizer(br.readLine()) ;
            return st.nextToken() ;
        } while(st == null || !st.hasMoreTokens())
                st = new StringTokenizer(br.readLine()) ; st == null || !st.hasMoreTokens() st == null st null !st.hasMoreTokens() st.hasMoreTokens() st.hasMoreTokens st st = new StringTokenizer(br.readLine()) st new StringTokenizer(br.readLine()) return st.nextToken() ; st.nextToken() st.nextToken st int nextInt() throws Exception { return Integer.parseInt(next()) ; } nextInt { return Integer.parseInt(next()) ; } return Integer.parseInt(next()) ; Integer.parseInt(next()) Integer.parseInt Integer next() next long nextLong() throws Exception {return Long.parseLong(next()) ; } nextLong {return Long.parseLong(next()) ; } return Long.parseLong(next()) ; Long.parseLong(next()) Long.parseLong Long next() next public class Main
{
    public static void main(String [] args) throws Exception
    {
        Scanner sc = new Scanner(System.in) ;
        PrintWriter out = new PrintWriter(System.out) ;
        char c = sc.next().charAt(0);
        if(Character.isUpperCase(c))
            out.println('A');
        else
            out.println('a');

        out.flush();
        out.close();
    }
    static class Scanner
    {
        BufferedReader br ;
        StringTokenizer st ;

        Scanner(InputStream in)
        {
            br = new BufferedReader(new InputStreamReader(in)) ;
        }

        String next() throws Exception
        {
            while(st == null || !st.hasMoreTokens())
                st = new StringTokenizer(br.readLine()) ;
            return st.nextToken() ;
        }

        int nextInt() throws Exception { return Integer.parseInt(next()) ; }

        long nextLong() throws Exception {return Long.parseLong(next()) ; }
    }
} public class Main
{
    public static void main(String [] args) throws Exception
    {
        Scanner sc = new Scanner(System.in) ;
        PrintWriter out = new PrintWriter(System.out) ;
        char c = sc.next().charAt(0);
        if(Character.isUpperCase(c))
            out.println('A');
        else
            out.println('a');

        out.flush();
        out.close();
    }
    static class Scanner
    {
        BufferedReader br ;
        StringTokenizer st ;

        Scanner(InputStream in)
        {
            br = new BufferedReader(new InputStreamReader(in)) ;
        }

        String next() throws Exception
        {
            while(st == null || !st.hasMoreTokens())
                st = new StringTokenizer(br.readLine()) ;
            return st.nextToken() ;
        }

        int nextInt() throws Exception { return Integer.parseInt(next()) ; }

        long nextLong() throws Exception {return Long.parseLong(next()) ; }
    }
} Main
import java.util.*;
import java.io.* ;

public class Main
{
    public static void main(String [] args) throws Exception
    {
        Scanner sc = new Scanner(System.in) ;
        PrintWriter out = new PrintWriter(System.out) ;
        char c = sc.next().charAt(0);
        if(Character.isUpperCase(c))
            out.println('A');
        else
            out.println('a');

        out.flush();
        out.close();
    }
    static class Scanner
    {
        BufferedReader br ;
        StringTokenizer st ;

        Scanner(InputStream in)
        {
            br = new BufferedReader(new InputStreamReader(in)) ;
        }

        String next() throws Exception
        {
            while(st == null || !st.hasMoreTokens())
                st = new StringTokenizer(br.readLine()) ;
            return st.nextToken() ;
        }

        int nextInt() throws Exception { return Integer.parseInt(next()) ; }

        long nextLong() throws Exception {return Long.parseLong(next()) ; }
    }
}