import java.util.Scanner;

/**
 * <p>ClassName:  </p>
 * <p>Description: </p>
 * <p>Company: </p>
 *
 * @author zhangyong
 * @version 1.0.0
 * @date 2020/6/24 20:46
 */
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String str = in.nextLine();
        Character a=str.charAt(0);
        if (a.charValue()>='A'&&a.charValue()<='Z'){
            System.out.println('A');
        }else if (a.charValue()>='a'&&a.charValue()<='z'){
            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