Bus

using System;

namespace Bus_Exam_24._11
{
    class Program
    {
        static void Main(string[] args)
        {
            int countsOfPassagersIn = int.Parse(Console.ReadLine());
            int countOfStops = int.Parse(Console.ReadLine());
            // int leftPassagers = 0;
            int outPassagers = 0;
            int inPassagers = 0;

            for (int i = 1; i <= countOfStops; i++)
            {
                outPassagers = int.Parse(Console.ReadLine());
                inPassagers = int.Parse(Console.ReadLine());

                countsOfPassagersIn -= outPassagers;
                countsOfPassagersIn += inPassagers;

              //  leftPassagers = (countsOfPassagersIn - outPassagers) + inPassagers;

                if (i % 2 == 1)
                {
                    countsOfPassagersIn += 2;
                }
                else if (i % 2 == 0)
                {
                    countsOfPassagersIn -= 2;
                }

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