import java.util.*;

public class Main {
 
	public static void main(String[] args) {
      Scanner sr = new Scanner(System.in);
      String str = sr.next();
      if(Character.isUpperCase(str.charAt(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