Inactive Interval of a day in TimeSpan, C#

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//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
            
            var activeIntervals = new List<Slot>
            {
                new Slot
                {
                    StartTime = new TimeSpan(10,0,0),
                    EndTime = new TimeSpan(12,0,0),
                },
                new Slot
                {
                    StartTime = new TimeSpan(12,0,0),
                    EndTime = new TimeSpan(13,0,0),
                },
                new Slot
                {
                    StartTime = new TimeSpan(16,0,0),
                    EndTime = new TimeSpan(22,0,0),
                }
            };
            
            
            activeIntervals = activeIntervals.OrderBy(x => x.StartTime).ToList();
                        
            var inActiveIntervals = new List<Slot>();
            TimeSpan start =  new TimeSpan(0,0,0);
            TimeSpan end =  new TimeSpan(24,0,0);
            
            for (int i = 0; i < activeIntervals.Count(); i++)
            {
                if (start < activeIntervals[i].StartTime) 
                {
                    inActiveIntervals.Add(new Slot { StartTime = start, EndTime = activeIntervals[i].StartTime });
                }
                start = activeIntervals[i].EndTime;
            }            
            if (start < end) 
            {
                inActiveIntervals.Add(new Slot { StartTime = start, EndTime = end });
                start = end;
            }
            for (int i = 0; i < inActiveIntervals.Count(); i++)
            {
                 Console.WriteLine(inActiveIntervals[i].StartTime.ToString() + " - " + inActiveIntervals[i].EndTime.ToString());
            }                        
        }
    }
    
    
    public class Slot
    {
        public TimeSpan StartTime { get; set; }
        public TimeSpan EndTime { get; set; }
    }
}

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Compilation time: 0,22 sec, absolute running time: 0,11 sec, cpu time: 0,09 sec, average memory usage: 14 Mb, average nr of threads: 3