Equal Pairs

using System;

namespace equalPairs
{
    class Program
    {
        public static void Main(string[] args)
        {
            int numberCount = int.Parse(Console.ReadLine());
            int firstSum= 0;
            int secondSum = 0;
            int diff = 0;
            int maxDiff = int.MinValue;

            for (int i=0; i<numberCount; i++)
            {
                secondSum = firstSum;

                int firstOfPair = int.Parse(Console.ReadLine());
                int secondOfPair = int.Parse(Console.ReadLine());

                firstSum = (firstOfPair + secondOfPair);

                if (i>0)
                {
                    diff = Math.Abs(firstSum - secondSum);

                    if (maxDiff < diff)
                    {
                        maxDiff = diff;
                    }
                }
            }

            if (maxDiff == 0 || numberCount == 1)
            {
                Console.WriteLine("Yes, value=" + firstSum);
            }
            else if (maxDiff>0)
            {
                Console.WriteLine("No, maxdiff=" + maxDiff);
            }

        }
    }
}