import java.util.*;
class Main{
  public static void main(String args[]){
    Scanner obj=new Scanner(System.in);
    
      char c=obj.next().charAt(0);
      if(Character.isLowerCase(c))
        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