import java.util.*;
import java.lang.*;
import java.math.*;
import java.io.*;
class Main{
	public static void main(String[] args) {
		InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
      	char c=in.next().charAt(0);
		if(c>=65 && c<=90)
			System.out.println('A');
		else
			System.out.println('a');
	} 
} import java.util.*; util.* java import java.lang.*; lang.* java import java.math.*; math.* java import java.io.*; io.* java class Main{
	public static void main(String[] args) {
		InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
      	char c=in.next().charAt(0);
		if(c>=65 && c<=90)
			System.out.println('A');
		else
			System.out.println('a');
	} 
} Main public static void main(String[] args) {
		InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
      	char c=in.next().charAt(0);
		if(c>=65 && c<=90)
			System.out.println('A');
		else
			System.out.println('a');
	} main {
		InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
      	char c=in.next().charAt(0);
		if(c>=65 && c<=90)
			System.out.println('A');
		else
			System.out.println('a');
	} InputStream inputStream = System.in; inputStream System.in System System.in OutputStream outputStream = System.out; outputStream System.out System System.out Scanner in = new Scanner(inputStream); in new Scanner(inputStream) PrintWriter out = new PrintWriter(outputStream); out new PrintWriter(outputStream) char c=in.next().charAt(0); c in.next().charAt(0) in.next().charAt in.next() in.next in 0 if(c>=65 && c<=90)
			System.out.println('A');
		else
			System.out.println('a'); c>=65 && c<=90 c>=65 c 65 c<=90 c 90 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.lang.*;
import java.math.*;
import java.io.*;
class Main{
	public static void main(String[] args) {
		InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
      	char c=in.next().charAt(0);
		if(c>=65 && c<=90)
			System.out.println('A');
		else
			System.out.println('a');
	} 
}
