using System;
using System.Collections.Generic;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            var tr = new List<string> { "1", "2", "3", "4", "5", "6", "7", "8" };
            for (int i = 0; i < tr.Count; i += 4)
                Console.WriteLine(string.Join("-", tr.GetRange(i, 4)));
            Console.ReadLine();
        }
    }
}