import java.util.*;

public class Main{
	public static void main(String[] args) {
		
		
		Scanner sc = new Scanner(System.in);

		String output = sc.next();
		char validate = output.charAt(0);

		if(Character.isUpperCase(validate)){
			output = "A";
		}else {
			output ="a";
		}
		
		System.out.println(output);
	}
}
/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