Raindrops

using System;

namespace Raindrops
{
    class MainClass
    {
        public static void Main(string[] args)
        {
            int regionsAmount = int.Parse(Console.ReadLine());
            decimal density = decimal.Parse(Console.ReadLine());

            decimal sum = 0;
            decimal regionCoefficient = 0;
            for (int i = 0; i < regionsAmount; i++)
            {
                string line = Console.ReadLine();
                string[] tokens = line.Split(' ');
                decimal raindropsCount = decimal.Parse(tokens[0]);
                decimal squareMeters = decimal.Parse(tokens[1]);

                sum += raindropsCount / squareMeters;
                regionCoefficient = sum / density;
            }
            if (density <= 0)
            {
                Console.WriteLine(sum);
            }
            else
            {
                Console.WriteLine("{0:F3}", regionCoefficient);
            }
        }
    }
}