using System;

using System.Collections.Generic;

using System.Linq;

using System.Threading.Tasks;

public class Program

{

    public static void Main()

    {

        decimal? x = (new decimal[] {0,1,2}).Sum(x => x); 

        decimal? y = (new decimal[] {}).Sum(x => x); 

        decimal? a = ((decimal?)(new decimal[] {}).Sum(x => x)) ?? 0; 

        Console.WriteLine(x);

        Console.WriteLine(y);

        Console.WriteLine(a);

    }

}