import java.math.BigInteger;
import java.util.*;
public class Main {
	static Map<Long,ArrayList<String>> l=new TreeMap<Long,ArrayList<String>>();
	static long p[];
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc=new Scanner(System.in);
		char c[]=sc.next().toCharArray();
		if(c[0]-'a'>=0&&c[0]-'b'<26) {
			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