using System;

​

public class Program

{

    public static void Main()

    {

    long a = 100;

    long b = -100;

    double jim = 0.0;

    // Long can be positive or negative.

    Console.WriteLine(a) ; 

    Console.WriteLine(b) ; // Long is very long.

    Console.WriteLine(long.MinValue ) ;

    Console.WriteLine(long .MaxValue ) ; // Long is 8 bytes.

    Console.WriteLine( sizeof  (long) ) ; // Default value is 0.

    Console.WriteLine( default  (long) ) ; // Long is System.Int64.

    Console.WriteLine( typeof  (long) ) ; 

    a = (long) 60 * 60 * 24 * 365;

    a = a * 1000;

    Console.WriteLine(a) ;

    Console.WriteLine(TimeSpan.FromMilliseconds(a) ) ;

    Console.WriteLine(DateTimeOffset.FromUnixTimeMilliseconds( 1597700921860 ) ) ; 

    var posixTime = DateTime.SpecifyKind(new DateTime(1970, 1, 1), DateTimeKind.Utc);

    var time = posixTime.AddMilliseconds(1597700921860);

    Console.WriteLine(time) ;

    }

    }

​