10.Crossroads

using System;
using System.Collections.Generic;

namespace _10_Crossroads
{
    class Program
    {
        static void Main(string[] args)
        {
            int greenlightDuration = int.Parse(Console.ReadLine());
            int freeWindowDuration = int.Parse(Console.ReadLine());
            Queue<string> cars = new Queue<string>();
            string command;
            int carsPassed = 0;
            while ((command = Console.ReadLine())!="END")
            {
                if (command!="green")
                {
                    cars.Enqueue(command);
                }
                else
                {
                    int green = greenlightDuration;
                    int freeWindow = freeWindowDuration;
                    while (green>0 && cars.Count!=0)
                    {
                        string car = cars.Peek();
                        Queue<char> currCar = new Queue<char>(cars.Dequeue());
                        while (green > 0)
                        {
                            if (!currCar.TryDequeue(out char result))
                            {
                                carsPassed++;
                                break;
                            }
                            green--;
                        }
                        if (currCar.Count!=0)
                        {
                            while (freeWindow>0)
                            {
                                if (!currCar.TryDequeue(out char result))
                                {
                                    carsPassed++;
                                    break;
                                }
                                freeWindow--;
                            }
                            if (currCar.Count!=0)
                            {
                                Console.WriteLine("A crash happened!");
                                Console.WriteLine($"{car} was hit at {currCar.Dequeue()}.");
                                return;
                            }
                        }
                    }
                }
            }
            Console.WriteLine("Everyone is safe.");
            Console.WriteLine($"{carsPassed} total cars passed the crossroads.");
        }
    }
}