Equal pairs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _04.Equal_Pairs
{
    class Program
    {
        static void Main(string[] args)
        {
            int numberEqual = int.Parse(Console.ReadLine());

            int sumFromNumbers = 0;
            bool areTheyEqual = true;
            int maxDiff = int.MinValue;
            int lastSum = 0;

            for (int i = 1; i <= numberEqual; i++)
            {
                int firstNumber = int.Parse(Console.ReadLine());
                int secondNumber = int.Parse(Console.ReadLine());
                int sumFromPair = firstNumber + secondNumber;

                if(i == 1)
                {
                    sumFromNumbers = sumFromPair;
                    lastSum = sumFromPair;
                }
                if(sumFromPair != sumFromNumbers)
                {
                    areTheyEqual = false;
                }
                if(Math.Abs(sumFromPair - lastSum) > maxDiff)
                {
                    maxDiff = Math.Abs(sumFromPair - lastSum);
                }
                lastSum = sumFromPair;
            }
            if(areTheyEqual)
            {
                Console.WriteLine($"Yes, value = {sumFromNumbers}");
            }
            else
            {
                Console.WriteLine($"No, maxdiff = {maxDiff}");
            }
        }
    }
}