Bus

using System;

namespace Bus
{
    class Program
    {
        static void Main(string[] args)
        {
            int passangersinBus = int.Parse(Console.ReadLine());
            int countStops = int.Parse(Console.ReadLine());


            for (int i = 0; i < countStops; i++)
            {
                int passangersOut = int.Parse(Console.ReadLine());
                int passangersIn = int.Parse(Console.ReadLine());


                if (i! % 2 == 0)
                {

                    passangersinBus += passangersIn + 2 - passangersOut;

                }
                else
                {
                    passangersinBus += passangersIn - passangersOut - 2;
                }
            }
            Console.WriteLine($"The final number of passengers is : {passangersinBus}");
        }
    }
}