using System;

using System.Linq;

using System.Collections;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var list = new List<int> (){-1,2,-3, 4, 5, 6, 21 };

        var sum = list.Where(x=>x%2!=0).Sum();

        Console.WriteLine(sum);

    }

}