import java.util.*;
import java.util.Arrays;
public class Main{
    public static void main(String[] args){
      Scanner sc = new Scanner(System.in);
      String x = sc.next();
      char []a = x.toCharArray();
      if(Character.isUpperCase(a[0])){
        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