помогите, не могу понять в чем ошыбка

import java.io.BufferedReader;
import java.io.InputStreamReader;

/*
User, Loser, Coder and Proger
*/

public class Solution {
    public static void main(String[] args) throws Exception {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        Person person = null;
        String key = null;

        while(true)
        {
            String s = reader.readLine();
            if(s.equals("user"))person = new User();
            else if(s.equals("loser"))person = new Loser();
            else if(s.equals("coder"))person = new Coder();
            else if(s.equals("proger"))person = new Proger();
            else break;

            doWork(person); //вызываем doWork

        }
    }

    public static void doWork(Person person) {
        if(person instanceof User)person.live();
        else if(person instanceof Loser)person.doNothing();
        else if(person instanceof Coder)person.coding();
        else if(person instanceof Proger)person.enjoy();
    }



    public class User implements Person {
        public void live() {
            System.out.println("Usually I just live.");
        }

		public void doNothing() {}

		@Override
		public void coding() {}

		@Override
		public void enjoy() {}
    }

    public class Loser implements Person {
        public void doNothing() {
            System.out.println("Usually I do nothing.");
        }

		@Override
		public void live() {}

		@Override
		public void coding() {}

		@Override
		public void enjoy() {}
    }

    public class Coder implements Person {
        public void coding() {
            System.out.println("Usually I create code.");
        }

		@Override
		public void live() {}

		@Override
		public void doNothing() {}

		@Override
		public void enjoy() {}
    }

     class Proger implements Person {
        public void enjoy() {
            System.out.println("Wonderful life!");
        }

		@Override
		public void live() {}

		@Override
		public void doNothing() {}

		@Override
		public void coding() {}
    }
}





public interface Person {
     	public void live();
     	public void doNothing();
     	public void coding();
     	public void enjoy();
}