import java.util.Scanner; 
class Main {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String input = scanner.next();
        String lower = input.toLowerCase();

        System.out.println( ( lower.equals(input) ) ? 'a': '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