import java.io.IOException;
import java.util.Scanner;

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

		char Alpa = sc.next().charAt(0);
		
		if(Character.isUpperCase(Alpa))
			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