	import java.util.Scanner;
	
	public class Main {
		public static void main(String[] args) {
			// TODO 自動生成されたメソッド・スタブ
			Scanner sc = new Scanner(System.in);
			char[] s = sc.next().toCharArray();
			if (Character.isUpperCase(s[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