import java.util.Scanner;
public class Main {
	int d,k;
	public void solve() {
	Scanner sc = new Scanner(System.in);
	String a = sc.next();

	if( Character.isUpperCase( a.charAt( 0 ) ) ) {
	    System.out.println("A");
	}else {
	    System.out.println("a");
	}
	}
	public static void main(String[] args) {
		new Main().solve();
	
	}
}

/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