/*package whatever //do not write package name here */
import java.util.*;
import java.lang.*;
import java.io.*;

class Main {
	public static void main (String[] args) {
// 		System.out.println("GfG!");
        Scanner input=new Scanner(System.in);
        String ch;
        ch=input.next();
        // char[] array=ch.toCharArray();
        // System.out.println("ch="  + ch.charAt(0));
        
        boolean ans=Character.isUpperCase(ch.charAt(0));
        if(ans)
            System.out.println("A");
        else  
             System.out.println("a");
        input.close();
	}
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz