import java.math.BigDecimal;
import java.time.LocalDate;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Scanner;
import java.util.concurrent.CountDownLatch;

public class Main {

	public static void main(String args[]) {

		Scanner scanner = new Scanner(System.in);

		String aString =  scanner.next();
		
		
		if(aString.charAt(0) >= 97 ) {
			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