View difference between Paste ID: aTt7auYq and q8AM7rn2

 import java.util.*;
 import java.util.stream.Collectors;
 
 public class demo {
     public static void main(String[] args) {
         Scanner scanner = new Scanner(System.in);
         int countCommands = Integer.parseInt(scanner.nextLine());
         List<String> names = new ArrayList<>();
         for (int i = 1; i <= countCommands ; i++) {
             String command = scanner.nextLine();
             //"{name} is going!" -> добавяме ако го няма; ако го има -> печатаме ...
             //"{name} is not going!" -> ако го има -> махаме; ако го няма -> печатаме
             String [] tokens = command.split("\\s+");
             //["{name}, "is", "going!"]
             //["{name}, "is", "not", "going!"]
             String name = tokens[0];
             if(tokens[2].equals("going!")) { //Going :)
                 if(names.contains(name)) {
                     System.out.printf("%s is already in the list!%n", name);
                 } else {
                     names.add(name);
                 }
             } else if (tokens[2].equals("not")) { //Not Going :(
                 if(names.contains(name)) {
                     names.remove(name);
                 } else {
                     System.out.printf("%s is not in the list!%n", name);
                 }
             }
 
         }
         printList(names);
 
     }
 
     private static void printList(List<String> names) {
         for (String name : names) {
             System.out.println(name);
         }
     }
 }