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

namespace ConsoleApplication25
{
    class Dane
    {
        public double h { get; set; }
        public double x0 { get; set; }
        public double y0 { get; set; }
        public double x1 { get; set; }

        public Dane()
        {
            Console.WriteLine("Podaj h: ");
            h = double.Parse(Console.ReadLine());

            Console.WriteLine("Podaj x0: ");
            x0 = double.Parse(Console.ReadLine());

            Console.WriteLine("Podaj y0: ");
            y0 = double.Parse(Console.ReadLine());

            Console.WriteLine("Podaj x1: ");
            x1 = double.Parse(Console.ReadLine());
        }
    }

    class Program
    {
        static double f(double x, double y)
        {
            return x + y;
        }
        static void Main(string[] args)
        {
            var dane = new Dane();

            double N = Math.Floor(Math.Abs((dane.x1 - dane.x0) / dane.h));
            double yn = dane.y0;
            double xn;


            for (int i = 0; i <= N; i++)
            {
                xn = dane.x0 + i * dane.h;

                double k1 = dane.h * f(xn, yn);
                double k2 = dane.h * f(xn + 0.5 * dane.h, yn + 0.5 * k1);
                double k3 = dane.h * f(xn + 0.5 * dane.h, yn + 0.5 * k2);
                double k4 = dane.h * f(xn + dane.h, yn + k3);

                yn = yn + (1.0 / 6) * (k1 + 2 * k2 + 2 * k3 + k4);
            }
            Console.WriteLine("y(" + dane.x1 + ") = " + yn);
            Console.ReadLine();
        }
    }
}