import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
      	Scanner sc = new Scanner(System.in);
      	String str = sc.next();
        if( Character.isUpperCase( str.charAt(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