import java.util.*;

public class Main{
public static void main(String[] args){
  Scanner sc = new Scanner(System.in);
  char value = sc.nextLine().toCharArray()[0];
  if(Character.isUpperCase(value))
    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