import java.util.*;

public class Main {
 
  public static void main(String[] args) {
    
    Scanner sc = new Scanner(System.in);
    
    String upperCases = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    String lowerCases = "abcdefghijklmnopqrstuvwxyz";
    
    String oneChar = sc.next();
    if (upperCases.indexOf(oneChar) >= 0) {
       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