import java.util.Scanner;

class Main{
  public static void main(String []a){
    Scanner sc=new Scanner(System.in);
    char ch=sc.next().charAt(0);
    
    if(ch>90){
      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