using System;

​

public class Program

{

    public static void Main()

    {

        long unixMilliseconds = 687481200000;

​

        DateTimeOffset dateTimeOffset = DateTimeOffset.FromUnixTimeMilliseconds(unixMilliseconds);

​

        TimeZoneInfo italianTimeZone = TimeZoneInfo.FindSystemTimeZoneById("Central European Standard Time");

​

        DateTimeOffset italianDateTimeOffset = TimeZoneInfo.ConvertTime(dateTimeOffset, italianTimeZone);

​

        DateTime italianDateTime = italianDateTimeOffset.DateTime;

​

        Console.WriteLine("Data e ora italiane: " + italianDateTime);

    }

}