using System;
using System.Net;
using System.Net.Http;
using System.Threading.Tasks;

public class Program
{
    private readonly HttpClient Client;
    private readonly CookieContainer CookieContainer = new CookieContainer();
    public Program()
    {
        var handler = new HttpClientHandler() { CookieContainer = CookieContainer };
        Client = new HttpClient(handler) { BaseAddress = new Uri("https://icstrvl.ru") };
        CookieContainer.Add(new Cookie("__ydma", "afx2232_32324", "/", Client.BaseAddress.Host)); // Задаем статичную Cookie __ydma, адрес которой == базовому адресу клиента.
    }

    public static void Main() => new Program().Run().GetAwaiter().GetResult();

    private async Task Run()
    {
        _ = await Client.GetAsync("/"); // Отправляем пустой запрос для получения Cookie tracking
        var response = await Client.GetAsync("/srch_v4/json/sdata.json?city=538625&cnt=14472441&spo=0&ct%5B%5D=5&tt%5B%5D=65977793&transport=all_transports&ad=2&ch=0&infant=0&ml%5B%5D=1771&d%5B%5D=7&date=2020-07-31&date1=2020-07-31&cur=0&mp=&nonstop=1&gf=1&pg=1&ver=1455&__mthd=getSearchResult&lttt=1");
        Console.WriteLine(await response.Content.ReadAsStringAsync());
    }

    // Метод получения Cookie, но он по сути тут лишний.
    //private async Task<Cookie> GetCookieAsync(string name)
    //{
    //    _ = await Client.GetAsync("/");
    //    var cookies = CookieContainer.GetCookies(Client.BaseAddress);
    //    return cookies[name];
    //}
}