public static class ListExtensions
    {
        public static int IndexOfSublist<T>(this IList<T> list, IList<T> sublist)
        {
            if(list.Count < sublist.Count) throw new ArgumentException();

            var indexOfSublist = -1;
            for(var i = 0; i < list.Count - sublist.Count + 1; ++i)
            {
                indexOfSublist = i;
                for(var j = 0; j < sublist.Count; ++j)
                {
                    if(!list[i + j].Equals(sublist[j]))
                    {
                        indexOfSublist = -1;
                        break;
                    }
                }

                if(indexOfSublist != -1)
                    break;
            }

            return indexOfSublist;
        }
    }