import java.util.Scanner;
class Main{
    public static void main(String []args){
          Scanner input=new Scanner(System.in);
      String temp=input.next();
      if(temp.toLowerCase().equals(temp)){
        System.out.print("a");
      }else{
        System.out.print("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