using System;

using System.Linq;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Début du script");

        var list = new List<string>{

            "abc", "g", "garage", "abeille", "gorille", "alice", "houx", "hache", "hey", "gargouillis"

        };

        //var results = from w in list

               //           group w by w;

        var result = list

    .Where(char.IsLetter)

    .GroupBy(c => c)

    .Select(g => new { Letter = g.Key, Count = g.Count() });

        //Console.WriteLine(result);

        Console.WriteLine(result.Select(x => string.Format("{0}: {1}", x.Letter, x.Count)));

​

    }

}