Browser

import java.util.*;
import java.sql.Timestamp;

public class Browser {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        List<String> tabs = new ArrayList<>();
        List<Long> timestamps = new ArrayList<>();
        String blankTab = "about:blank";
        Timestamp timestamp = new Timestamp(System.currentTimeMillis());
        long ts = timestamp.getTime();

        tabs.add(blankTab);
        timestamps.add(ts);

        String currentTab = blankTab;

        String input = scanner.nextLine();

        while (!input.equals("END")) {
            String[] tokens = input.split(" ");
            String command = tokens[0];
            switch (command) {
                case "GO":
                    int index = tabs.indexOf(currentTab);
                    currentTab = tokens[1];
                    timestamp = new Timestamp(System.currentTimeMillis());
                    ts = timestamp.getTime();
                    tabs.set(index, currentTab);
                    timestamps.set(index, ts);
                    break;
                case "INSERT":
                    index = tabs.indexOf(currentTab);
                    currentTab = tokens[1];
                    timestamp = new Timestamp(System.currentTimeMillis());
                    ts = timestamp.getTime();
                    tabs.add(index + 1, currentTab);
                    timestamps.add(index + 1, ts);
                    break;
                case "BACK":
                    index = tabs.indexOf(currentTab);
                    if (index > 0) {
                        currentTab = tabs.get(index - 1);
                    }
                    break;
                case "FORWARD":
                    index = tabs.indexOf(currentTab);
                    if (index != tabs.size() - 1) {
                        currentTab = tabs.get(index + 1);
                    }
                    break;
                case "REMOVE":
                    index = tabs.indexOf(currentTab);
                    if (index < tabs.size() - 1) {
                        currentTab = tabs.get(index + 1);
                        tabs.remove(index);
                        timestamps.remove(index);
                    } else if (index > 0) {
                        currentTab = tabs.get(0);
                        tabs.remove(index);
                        timestamps.remove(index);
                    } else {
                        tabs.clear();
                        timestamps.clear();
                        tabs.add(blankTab);
                        timestamp = new Timestamp(System.currentTimeMillis());
                        ts = timestamp.getTime();
                        timestamps.add(ts);
                    }
                    break;
                case "PRINT":
                    for (int i = 0; i < tabs.size(); i++) {
                        if (tabs.get(i).equals(currentTab)) {
                            System.out.printf(">%s %d%n", tabs.get(i), timestamps.get(i));
                        } else {
                            System.out.printf("%s %d%n", tabs.get(i), timestamps.get(i));
                        }
                    }
                    break;
                default:
                    break;
            }

            input = scanner.nextLine();
        }

    }
}