using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(CommaQuibblify(new string[] { }));

        Console.WriteLine(CommaQuibblify(new string[] { "ABC" }));

        Console.WriteLine(CommaQuibblify(new string[] { "ABC", "DEF" }));

        Console.WriteLine(CommaQuibblify(new string[] { "ABC", "DEF", "G", "H" }));

    }

    public static string CommaQuibblify(IEnumerable<string> items)

    {

        var head = string.Join(", ", items.SkipLast(2).Append(""));

        var tail = string.Join(" and ", items.TakeLast(2));

        return '{' + head + tail + '}';

    }

}