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

namespace Task1
{
    class Program
    {
        static double Calc(double a1, double a2, double h)
        {
            double ans = 0;
            int i = 0;

            while (a1 + i * h < a2)
            {
                double p1 = Math.Sin(a1 + i * h) * Math.Cos(a1 + i * h) + Math.Cos(a1 + i * h);
                double p2;
                double h1 = h;
                if (a1 + i * h + h < a2)
                {
                    p2 = Math.Sin(a1 + i * h + h) * Math.Cos(a1 + i * h + h) + Math.Cos(a1 + i * h + h);
                }
                else
                {
                    p2 = Math.Sin(a2) * Math.Cos(a2) + Math.Cos(a2);
                    h1 = (a2 - a1 + i * h);
                }
                if (p1 * p2 >= 0)
                {
                    if (p1 < 0)
                    {
                        ans += Math.Max(p1, p2) * h1;
                        ans -= (h1 * Math.Abs(p2 - p1)) / 2;
                    }
                    else
                    {
                        ans += Math.Min(p1, p2) * h1;
                        ans += (h1 * Math.Abs(p2 - p1)) / 2;
                    }
                }
                else
                {
                    ans += (h1 * (p1)) / (2+2*p1/p2);
                    ans += (h1 * (p2)) / (2+2*p2/p1);
                }
                i++;
            }

                return ans;
        }

        static void Main(string[] args)
        {
            double sum = -1;
            double a = 0, b = 0, h = 0;
            int N = 0;
            while (sum != 0)
            {
                Console.Write("Введите а= ");
                a = Double.Parse(Console.ReadLine());
                Console.Write("Введите b= ");
                b = Double.Parse(Console.ReadLine());
                if (b < a)
                {
                    Console.WriteLine("Неправильно введен отрезок");
                    sum = -1;
                }
                else sum = 0;
            }
            sum = -1;
            while (sum != 0)
            {
                Console.Write("Введите шаг h= ");
                h = Double.Parse(Console.ReadLine());
                if (h <= 0)
                {
                    Console.WriteLine("Неправильно введен шаг");
                    sum = -1;
                }
                else sum = 0;
            }
            sum = -1;
            while (sum != 0)
            {
                Console.Write("Введите N= ");
                N = Int32.Parse(Console.ReadLine());
                if (N <= 0)
                {

                    Console.WriteLine("Неправильно введен N");
                    sum = -1;
                }
                else sum = 0;
            }
            double ans = 0;
            Task<double>[] task = new Task<double>[N];
            double dx = (b - a) / N;
            for (int i = 0; i < N; i++)
            {
                task[i] = new Task<double>(() => Calc(a+dx*(i), a+dx*(i+1), h));
                task[i].Start();
            }
            for (int i = 0; i < N; i++)
            {
                ans += task[i].Result;
            }
            Console.Write("Ответ: ");
            Console.WriteLine(ans);
            Console.ReadKey();
        }
    }
}