import java.util.Scanner;
import java.lang.*;
class Main{
      public static void main(String args[]){
	Scanner sc = new Scanner(System.in);
	String s = sc.next();
	if(Character.isLowerCase(s.charAt(0))){
	    System.out.println("a");
	}else{
	    System.out.println("A");
	}
	sc.close();
      }
}

/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