import java.util.Scanner;
import java.util.regex.*;
public class Main
{
  public static void main(String[] args)
  {
    Scanner sc = new Scanner(System.in);
    String str = sc.nextLine();
    
    if(Pattern.matches("[A-Z]",str))
      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