Merge overlapping intervals

using System;
using System.Collections.Generic;

class Program
{
    class Interval
    {
        public int Start { get; set; }
        public int End { get; set; }
        public Interval(int start, int end) { Start = start; End = end; }
    }

    static List<Interval> MergeIntervals(List<Interval> intervals)
    {
        intervals.Sort((first, second) => first.Start.CompareTo(second.Start));
        var merged = new List<Interval>();

        foreach (Interval interval in intervals)
        {
            if (merged.Count == 0 || merged[merged.Count - 1].End < interval.Start)
                merged.Add(new Interval(interval.Start, interval.End));
            else
                merged[merged.Count - 1].End = Math.Max(merged[merged.Count - 1].End, interval.End);
        }
        return merged;
    }

    static void Main()
    {
        var intervals = new List<Interval>
        {
            new Interval(1, 3), new Interval(2, 6),
            new Interval(8, 10), new Interval(15, 18)
        };
        var labels = new List<string>();
        foreach (Interval interval in MergeIntervals(intervals))
            labels.Add(interval.Start + "-" + interval.End);
        Console.WriteLine(string.Join(", ", labels));
    }
}