public class UserService {

  private UserRepository userRepository;

  public UserService(UserRepository userRepository) {
    this.userRepository = userRepository;
  }

  public User getUserById(long id) {
    try {
      return userRepository.getUserById(id);
    } catch (Exception e) {
      // Log the exception here
      System.out.println("An error occurred while fetching the user: " + e.getMessage());
      return null;
    }
  }
}

public class UserRepository {

  public User getUserById(long id) throws Exception {
    // Database query to fetch the user
    if (id < 0) {
      throw new Exception("Invalid user id");
    }
    // Return the user object
    return new User(id, "John Doe");
  }
}

public class User {

  private long id;
  private String name;

  public User(long id, String name) {
    this.id = id;
    this.name = name;
  }

  public long getId() {
    return id;
  }

  public String getName() {
    return name;
  }
}

public class Solution {
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        ListNode head = new ListNode(0);
        ListNode handler = head;
        while(l1 != null && l2 != null) {
            if (l1.val <= l2.val) {
                handler.next = l1;
                l1 = l1.next;
            } else {
                handler.next = l2;
                l2 = l2.next;
            }
            handler = handler.next;
        }
        
        if (l1 != null) {
            handler.next = l1;
        } else if (l2 != null) {
            handler.next = l2;
        }
        
        return head.next;
    }
}

public class Daedalus extends Athenian
{
	private Story story;
	public ArrayList<Skill> skills = new ArrayList<Skill>();
	public ArrayList<Athenian> children = new ArrayList<Athenian>();
	
	public Daedalus(Story story, ArrayList<Skill> inherentSkills)
	{
	if(story != null)
	System.out.println("ERROR No one is created with a story.");

	skills.add(inherentSkills);
	}

	public Momento advanceStory(Scene s)
	{
	System.err.println("ERROR Don't know how to proceed...");
	}
}


//██╗  ░█████╗░███╗░░░███╗  ██████╗░░█████╗░███████╗██████╗░░█████╗░██╗░░░░░██╗░░░██╗░██████╗
//██║  ██╔══██╗████╗░████║  ██╔══██╗██╔══██╗██╔════╝██╔══██╗██╔══██╗██║░░░░░██║░░░██║██╔════╝
//██║  ███████║██╔████╔██║  ██║░░██║███████║█████╗░░██║░░██║███████║██║░░░░░██║░░░██║╚█████╗░
//██║  ██╔══██║██║╚██╔╝██║  ██║░░██║██╔══██║██╔══╝░░██║░░██║██╔══██║██║░░░░░██║░░░██║░╚═══██╗
//██║  ██║░░██║██║░╚═╝░██║  ██████╔╝██║░░██║███████╗██████╔╝██║░░██║███████╗╚██████╔╝██████╔╝
//╚═╝  ╚═╝░░╚═╝╚═╝░░░░░╚═╝  ╚═════╝░╚═╝░░╚═╝╚══════╝╚═════╝░╚═╝░░╚═╝╚══════╝░╚═════╝░╚═════╝░

import java.util.Scanner;

/* In Heaven, the seed is tall and the oak small / It's input vital 
	* "The al-Madinatian," verse 236-37 
	* tinyurl.com/17snqkfv
	* email answer to [email protected]
	**/

public class Main
{
	public static void main(String args[])
	{
		int x = 0;
		int a, c, m = 10000;
		
		Scanner in = new Scanner(System.in);
		
		System.out.println("Please enter a seed, maximum 3000000:");
		x = in.nextInt();
		
		System.out.println("Please input a number, maximum 29:");
		a = in.nextInt();
		
		System.out.println("Please input a number, maximum 999999:");
		c = in.nextInt();
		
		char menu = 'y';
		while(menu != 'n')
		{
			x = (a*x + c) % m;
			
			System.out.println("The next number is " + x + "\nWould you like another? (y/n)");
			menu = in.next().charAt(0);
		}
	}
}

//██╗  ░█████╗░███╗░░░███╗  ██████╗░░█████╗░███████╗██████╗░░█████╗░██╗░░░░░██╗░░░██╗░██████╗
//██║  ██╔══██╗████╗░████║  ██╔══██╗██╔══██╗██╔════╝██╔══██╗██╔══██╗██║░░░░░██║░░░██║██╔════╝
//██║  ███████║██╔████╔██║  ██║░░██║███████║█████╗░░██║░░██║███████║██║░░░░░██║░░░██║╚█████╗░
//██║  ██╔══██║██║╚██╔╝██║  ██║░░██║██╔══██║██╔══╝░░██║░░██║██╔══██║██║░░░░░██║░░░██║░╚═══██╗
//██║  ██║░░██║██║░╚═╝░██║  ██████╔╝██║░░██║███████╗██████╔╝██║░░██║███████╗╚██████╔╝██████╔╝
//╚═╝  ╚═╝░░╚═╝╚═╝░░░░░╚═╝  ╚═════╝░╚═╝░░╚═╝╚══════╝╚═════╝░╚═╝░░╚═╝╚══════╝░╚═════╝░╚═════╝░

public class Main {
  public static void main(String[] args) {
    System.out.println("Hello World");
  }
}

public static String addBinary(){
 // The two input Strings, containing the binary representation of the two values:
    String input0 = "1010";
    String input1 = "10";

    // Use as radix 2 because it's binary    
    int number0 = Integer.parseInt(input0, 2);
    int number1 = Integer.parseInt(input1, 2);

    int sum = number0 + number1;
    return Integer.toBinaryString(sum); //returns the answer as a binary value;
}