using System;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

     public class Interval

        {

            public int Start { get; set; }

​

            public int End { get; set; }

        };

​

        enum Node

        {

            Unvisited = 0,

            Visited = 1,

            Used = 2

        };

    Node[] tree;

    public void Calculate()

    {

            var secondryIntervalsAsDates = new List<Tuple<DateTime,DateTime>> { new Tuple<DateTime, DateTime>( new DateTime(2015, 03, 15, 4, 0, 0), new DateTime(2015, 03, 15, 5, 0, 0))};

            var mainInvtervalAsDate = new Tuple<DateTime, DateTime>(new DateTime(2015, 03, 15, 3, 0, 0), new DateTime(2015, 03, 15, 7, 0, 0));

            // calculate 

            var startDate = secondryIntervalsAsDates.Union( new List<Tuple<DateTime,DateTime>>{mainInvtervalAsDate}).Min(s => s.Item1).AddMinutes(-1);

            var endDate = secondryIntervalsAsDates.Union(new List<Tuple<DateTime, DateTime>> { mainInvtervalAsDate }).Max(s => s.Item2);

​

            var mainInvterval = new Interval { Start = (int)(mainInvtervalAsDate.Item1 - startDate).TotalMinutes, End = (int)(mainInvtervalAsDate.Item2 - startDate).TotalMinutes };

            var wholeInterval = new Interval { Start = 1, End = (int)(endDate - startDate).TotalMinutes};

            var secondaryIntervals = secondryIntervalsAsDates.Select(s => new Interval { Start = (int)(s.Item1 - startDate).TotalMinutes, End = (int)(s.Item2 - startDate).TotalMinutes}).ToList();

            tree = new Node[wholeInterval.End * 2 + 1];

            secondaryIntervals.ForEach(s => Search(wholeInterval, s, 1));

            var result = Search(wholeInterval, mainInvterval, 1);

            var minutes = result.Sum(r => r.End - r.Start) + result.Count();

            Console.WriteLine(minutes);

    }

    public IEnumerable<Interval> Search(Interval current, Interval searching, int index)

        {

            if (tree[index] == Node.Used || searching.End < searching.Start)

            {

                return new List<Interval>();

            }

            if (tree[index] == Node.Unvisited && current.Start == searching.Start && current.End == searching.End)

            {

                tree[index] = Node.Used;

                return new List<Interval> { current };

            }

            tree[index] = Node.Visited;

            return Search(new Interval { Start = current.Start, End = current.Start + (current.End - current.Start) / 2 },

                      new Interval { Start = searching.Start, End = Math.Min(searching.End, current.Start + (current.End - current.Start) / 2)  }, index * 2).Union(

                Search(new Interval { Start = current.Start + (current.End - current.Start) / 2 + 1 , End = current.End},

                  new Interval { Start = Math.Max(searching.Start, current.Start + (current.End - current.Start) / 2 + 1), End = searching.End }, index * 2 + 1));

        }

    public  void Main()

    {

        Calculate();

    }

}