import java.util.*;
class Main {
  static Scanner scan = new Scanner(System.in);
  public static void main(String[] args) {
  	char c = scan.next().charAt(0);
    if(c >= 'A' && c <= 'Z'){
    	System.out.println("A");   
    }else if (c >= 'a' && c <= 'z'){
    	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