import java.util.*;


public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String line = sc.nextLine();

        if(line.equals("a")||
        line.equals("b")||
        line.equals("c")||
        line.equals("d")||
        line.equals("e")||
        line.equals("f")||
        line.equals("g")||
        line.equals("h")||
        line.equals("i")||
        line.equals("j")||
        line.equals("k")||
        line.equals("l")||
        line.equals("m")||
        line.equals("n")||
        line.equals("o")||
        line.equals("p")||
        line.equals("q")||
        line.equals("r")||
        line.equals("s")||
        line.equals("t")||
        line.equals("u")||
        line.equals("v")||
        line.equals("w")||
        line.equals("x")||
        line.equals("y")||
        line.equals("z")){
          System.out.println("a");
        }else{
          System.out.println("A");
        }
      
    }
}


/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