using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    class Data

    {

        public int id_seansu { get; set; }

        public TimeSpan godzina { get; set; }

        public DateTime data { get; set; }

        public int id_filmu { get; set; }

    }

    static IEnumerable<Data> seanses;

    public static void Main()

    {

        seanses = new List<Data>

        {

            new Data() { id_seansu = 1, data = DateTime.Parse("07.12.2016"), id_filmu = 1 },

            new Data() { id_seansu = 1, data = DateTime.Parse("07.12.2016"), id_filmu = 1 },

            new Data() { id_seansu = 1, data = DateTime.Parse("08.12.2016"), id_filmu = 1 },

            new Data() { id_seansu = 1, data = DateTime.Parse("08.12.2016"), id_filmu = 1 },

            new Data() { id_seansu = 1, data = DateTime.Parse("10.12.2016"), id_filmu = 1 },

        };

        IEnumerable<DateTime> dataSource = (from availableDate in seanses

                                        where availableDate.id_filmu == 1

                                        orderby availableDate.data

                                        select availableDate.data).Distinct();

        foreach (DateTime item in dataSource)

        {

            Console.WriteLine(item);

        }

    }

}