Bus

using System;

namespace Bus
{
    class Program
    {
        static void Main(string[] args)
        {
            int startPassengersNumber = int.Parse(Console.ReadLine());
            int passengersOn = 0;
            int passengersOff = 0;
            int conductors = 0;
            int finalPassengers = 0;
            int stopsNumber = int.Parse(Console.ReadLine());


            for (int i = 1; i <= stopsNumber; i++)
            {
                passengersOff = int.Parse(Console.ReadLine());
                passengersOn = int.Parse(Console.ReadLine());

                if (i % 2 > 0)
                {
                    conductors = 2;
                }
                else if (i % 2 == 0)
                {
                    conductors = -2;
                }

                finalPassengers = startPassengersNumber + passengersOn - passengersOff + conductors;
                startPassengersNumber = finalPassengers;
            }

            Console.WriteLine($"The final number of passengers is : {finalPassengers}");
        }
    }
}