using System;

using System.Globalization;

public class Program

{

    public static void Main()

    {

        var start = DateTime.Parse("2021-10-31T02:50:00.0000000+02:00").ToUniversalTime();

        var end = DateTime.Parse("2021-10-31T02:10:00.0000000+01:00").ToUniversalTime();

        Console.WriteLine("Start UTC: {0}", start);

        Console.WriteLine("End UTC: {0}", end);

        Console.WriteLine();

        var tz = TimeZoneInfo.FindSystemTimeZoneById("W. Europe Standard Time");

        var convertedStart = TimeZoneInfo.ConvertTimeFromUtc(start, tz);

        var convertedEnd = TimeZoneInfo.ConvertTimeFromUtc(end, tz);

        Console.WriteLine("Start conv: {0}", convertedStart);

        Console.WriteLine("End conv: {0}", convertedEnd);

    }

}