import java.math.BigInteger;
import java.util.*;
public class Main {
	static Map<Long,ArrayList<String>> l=new TreeMap<Long,ArrayList<String>>();
	static long p[];
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc=new Scanner(System.in);
		char c[]=sc.next().toCharArray();
		if(c[0]-'a'>=0&&c[0]-'b'<26) {
			System.out.println("a");
		}else {
			System.out.println("A");
		}
	}
	
	
}

  import java.math.BigInteger; BigInteger java.math import java.util.*; util.* java public class Main {
	static Map<Long,ArrayList<String>> l=new TreeMap<Long,ArrayList<String>>();
	static long p[];
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc=new Scanner(System.in);
		char c[]=sc.next().toCharArray();
		if(c[0]-'a'>=0&&c[0]-'b'<26) {
			System.out.println("a");
		}else {
			System.out.println("A");
		}
	}
	
	
} Main static Map<Long,ArrayList<String>> l=new TreeMap<Long,ArrayList<String>>(); l new TreeMap<Long,ArrayList<String>>() static long p[]; p public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc=new Scanner(System.in);
		char c[]=sc.next().toCharArray();
		if(c[0]-'a'>=0&&c[0]-'b'<26) {
			System.out.println("a");
		}else {
			System.out.println("A");
		}
	} main {
		// TODO Auto-generated method stub
		Scanner sc=new Scanner(System.in);
		char c[]=sc.next().toCharArray();
		if(c[0]-'a'>=0&&c[0]-'b'<26) {
			System.out.println("a");
		}else {
			System.out.println("A");
		}
	} Scanner sc=new Scanner(System.in); sc new Scanner(System.in) char c[]=sc.next().toCharArray(); c sc.next().toCharArray() sc.next().toCharArray sc.next() sc.next sc if(c[0]-'a'>=0&&c[0]-'b'<26) {
			System.out.println("a");
		}else {
			System.out.println("A");
		} c[0]-'a'>=0&&c[0]-'b'<26 c[0]-'a'>=0 c[0]-'a' c[0] c 0 'a' 0 c[0]-'b'<26 c[0]-'b' c[0] c 0 'b' 26 {
			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 {
	static Map<Long,ArrayList<String>> l=new TreeMap<Long,ArrayList<String>>();
	static long p[];
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc=new Scanner(System.in);
		char c[]=sc.next().toCharArray();
		if(c[0]-'a'>=0&&c[0]-'b'<26) {
			System.out.println("a");
		}else {
			System.out.println("A");
		}
	}
	
	
} public class Main {
	static Map<Long,ArrayList<String>> l=new TreeMap<Long,ArrayList<String>>();
	static long p[];
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc=new Scanner(System.in);
		char c[]=sc.next().toCharArray();
		if(c[0]-'a'>=0&&c[0]-'b'<26) {
			System.out.println("a");
		}else {
			System.out.println("A");
		}
	}
	
	
} Main
import java.math.BigInteger;
import java.util.*;
public class Main {
	static Map<Long,ArrayList<String>> l=new TreeMap<Long,ArrayList<String>>();
	static long p[];
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc=new Scanner(System.in);
		char c[]=sc.next().toCharArray();
		if(c[0]-'a'>=0&&c[0]-'b'<26) {
			System.out.println("a");
		}else {
			System.out.println("A");
		}
	}
	
	
}

 
