import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		char ch = sc.next().trim().charAt(0);
		
		StringBuilder sb = new StringBuilder();
		
		if(ch >= 'A' && ch <='Z')
			sb.append('A' + "\n");
		else if(ch >='a' && ch <= 'z')
			sb.append('a' + "\n");
		
		sc.close();
		
		System.out.println(sb);
	}

}
/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