using System;

using System.Linq;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        List<OpeningHour> openings = new List<OpeningHour>(){

            new OpeningHour(){

                Day = "Lundi",

                Hour = "09h - 20h"

            },

            new OpeningHour(){

                Day = "Mardi",

                Hour = "09h - 20h"

            },

            new OpeningHour(){

                Day = "Mercredi",

                Hour = "09h - 20h"

            },

            new OpeningHour(){

                Day = "Jeudi",

                Hour = "10h - 18h"

            },

            new OpeningHour(){

                Day = "Vendredi",

                Hour = "10h - 18h"

            },

            new OpeningHour(){

                Day = "Samedi",

                Hour = "09h - 20h"

            },

            new OpeningHour(){

                Day = "Dimanche",

                Hour = "closed"

            },

        };

        Dictionary<string, List<int>> groupByHour = new Dictionary<string, List<int>>();

        for(var i=0;i<openings.Count;i++){

            var opening = openings[i];

            if(!groupByHour.ContainsKey(opening.Hour)){

                groupByHour[opening.Hour]  = new List<int>();

            }

            var val = groupByHour[opening.Hour];

            val.Add(i);

        }

        Dictionary<string, List<int>> groupByDiff = new Dictionary<string, List<int>>();

        foreach(var key in groupByHour.Keys){

            var list = groupByHour[key];

            var index = 1;

            for(var i=0;i<list.Count;i++){

                var currentKey = key+index;

                if(!groupByDiff.ContainsKey(currentKey)){

                    groupByDiff[currentKey]  = new List<int>();

                }

                var val = groupByDiff[currentKey];

                val.Add(list[i]);

                if(i+1 !=list.Count && list[i+1]-list[i] != 1){                 

                    index++;

                }

            }

        }

        var orderList = new Dictionary<int, string>();

        foreach(var key in groupByDiff.Keys){

            var list = groupByDiff[key];

            var begin = openings[list.Min()];

            var end = openings[list.Max()];

            var text = begin.Day+ " till "+end.Day+ " : "+begin.Hour;

            orderList.Add(list.Max(), text);

        }

        var orderKey = orderList.Keys.AsEnumerable().ToList();

        orderKey.Sort();

        foreach(var key in orderKey){

            Console.WriteLine(orderList[key]);

        }

    }

}

​

class OpeningHour {

    public string Day {get;set;}

    public string Hour {get;set;}

​

}