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

class Main{
    
	public static void main(String args[]){
	    
    	Scanner in = new Scanner(System.in);
      	char c = in.next().charAt(0);
		
		if((int)c > 64 && (int)c <91)
			System.out.println("A");
		else
			System.out.println("a");
		
    }
 
} import java.util.*; util.* java import java.io.*; io.* java import java.lang.*; lang.* java class Main{
    
	public static void main(String args[]){
	    
    	Scanner in = new Scanner(System.in);
      	char c = in.next().charAt(0);
		
		if((int)c > 64 && (int)c <91)
			System.out.println("A");
		else
			System.out.println("a");
		
    }
 
} Main public static void main(String args[]){
	    
    	Scanner in = new Scanner(System.in);
      	char c = in.next().charAt(0);
		
		if((int)c > 64 && (int)c <91)
			System.out.println("A");
		else
			System.out.println("a");
		
    } main {
	    
    	Scanner in = new Scanner(System.in);
      	char c = in.next().charAt(0);
		
		if((int)c > 64 && (int)c <91)
			System.out.println("A");
		else
			System.out.println("a");
		
    } Scanner in = new Scanner(System.in); in new Scanner(System.in) char c = in.next().charAt(0); c in.next().charAt(0) in.next().charAt in.next() in.next in 0 if((int)c > 64 && (int)c <91)
			System.out.println("A");
		else
			System.out.println("a"); (int)c > 64 && (int)c <91 (int)c > 64 (int)c 64 (int)c <91 (int)c 91 System.out.println("A") System.out.println System.out System System.out "A" System.out.println("a") System.out.println System.out System System.out "a" String args[] args
import java.util.*;
import java.io.*;
import java.lang.*;

class Main{
    
	public static void main(String args[]){
	    
    	Scanner in = new Scanner(System.in);
      	char c = in.next().charAt(0);
		
		if((int)c > 64 && (int)c <91)
			System.out.println("A");
		else
			System.out.println("a");
		
    }
 
}