using System;
using System.Collections.Generic;

class Schedule {
	public TimeSpan Begin {get;set;}
	public TimeSpan End {get;set;}
}
class GalaxySector {
	public TimeSpan Begin {get;set;}
	public TimeSpan End {get;set;}
}

public class Test
{
	
	private static readonly TimeSpan HalfHour = TimeSpan.Parse("0:30");
	
	private static IEnumerable<Schedule> Group(IList<GalaxySector> all) {
		// Protect from division by zero
		if (all.Count == 0) {
			yield break;
		}
		// Find initial location
		var pos = 0;
		while (pos < all.Count) {
			var prior = (pos + all.Count - 1) % all.Count;
			if (all[prior].End+HalfHour >= all[pos].Begin) {
				pos++;
			} else {
				break;
			}
		}
		pos = pos % all.Count;
		// Start grouping items together
		var stop = pos;
		do {
			var start = pos;
			var next = (pos+1) % all.Count;
			while (next != stop && all[pos].End+HalfHour >= all[next].Begin) {
				pos = next;
				next = (pos+1) % all.Count;
			}
			yield return new Schedule {Begin = all[start].Begin, End = all[pos].End};
			pos = next;
		} while (pos != stop);
	}
	
	public static void Main()
	{
		var all = new GalaxySector[] {
			new GalaxySector {Begin=TimeSpan.Parse("0:15"), End=TimeSpan.Parse("2:30")}
		,   new GalaxySector {Begin=TimeSpan.Parse("2:45"), End=TimeSpan.Parse("3:30")}
		,	new GalaxySector {Begin=TimeSpan.Parse("8:00"), End=TimeSpan.Parse("9:30")}
		,	new GalaxySector {Begin=TimeSpan.Parse("10:00"), End=TimeSpan.Parse("11:00")}
		,	new GalaxySector {Begin=TimeSpan.Parse("11:20"), End=TimeSpan.Parse("12:30")}
		,	new GalaxySector {Begin=TimeSpan.Parse("14:00"), End=TimeSpan.Parse("16:00")}
		,	new GalaxySector {Begin=TimeSpan.Parse("18:30"), End=TimeSpan.Parse("19:30")}
		,	new GalaxySector {Begin=TimeSpan.Parse("19:45"), End=TimeSpan.Parse("21:00")}
		,	new GalaxySector {Begin=TimeSpan.Parse("22:00"), End=TimeSpan.Parse("23:50")}
		};
		foreach (var sched in Group(all)) {
			Console.WriteLine("{0}..{1}", sched.Begin, sched.End);
		}
	}
}