Program.cs

using System;
using System.Net.Http;
using System.Text;
using System.Threading.Tasks;
using System.Web;
using NmuScheduleParser;

namespace NSParserExample
{
    internal class Program
    {
        static void Main(string[] args)
        {
            Console.OutputEncoding = Encoding.UTF8;
            MainAsync().GetAwaiter().GetResult();
        }
  
        static async Task MainAsync()
        {
            var htmlRaw = await DownloadHtmlSchedule(@"https://nmc.udu.edu.ua", "31ІПЗ");
            var schedule = ScheduleParser.GetSchedule(htmlRaw);
            /* 
                Schedule:
                    List<Day> Days

                Day: 
                    string Date
                    string DayOfWeek
                    List<Class> Classes

                Class:
                    string StartTime
                    string EndTime
                    ClassInfo FirstClass
                    ClassInfo SecondClass

                ClassInfo:
                    string[] Description
                    string NameRemote
            */
            
            Console.WriteLine(schedule); // print override ToString()
            
            // Example using a model.
            int classCount = 0;
            if (schedule?.Days != null)
                foreach (var day in schedule.Days)
                    classCount += day.Classes.Count;

            var classAllMinutes = classCount * 80;
            Console.WriteLine("\nClass count: {0}, It's {1} hours and {2} minutes", classCount, classAllMinutes / 60, classAllMinutes % 60);

            Console.WriteLine("\nPress any key...");
            Console.ReadKey();
        }

        static async Task<string> DownloadHtmlSchedule(string domain, string groupName, string startDate = "", string endDate = "")
        {
            Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
            var encodingWin1251 = Encoding.GetEncoding("windows-1251");
            groupName = HttpUtility.UrlEncode(groupName, encodingWin1251);

            var bodyParam = $"group={groupName}&sdate={startDate}&edate={endDate}";
            var body = Encoding.UTF8.GetBytes(bodyParam);
            var client = new HttpClient { BaseAddress = new Uri(domain) };

            //n=700 should be as url parameter, otherwise it doesn't work
            var response = await client.PostAsync(@"cgi-bin/timetable.cgi?n=700", new ByteArrayContent(body));
            var responseContentBytes = await response.Content.ReadAsByteArrayAsync();

            if (!response.IsSuccessStatusCode)
                Console.WriteLine($"Status code download: {response.StatusCode}");

            return encodingWin1251.GetString(responseContentBytes);
        }
    }
}