var temp = "";
            var cond = false;
            var list = new List<string>();
            while ((temp = Console.ReadLine()) != "")
            {
                list.Add("");
                foreach (var item in temp)
                    if (char.IsLetter(item))
                        if (cond == false)
                        {
                            cond = true;
                            list[list.Count() - 1] += char.ToUpper(item);
                        }
                        else
                            list[list.Count() - 1] += char.ToLower(item);
                    else if ((item == 33) || (item == 46) || (item == 63))
                    {
                        cond = false;
                        list[list.Count() - 1] += item;
                    }
                    else
                        list[list.Count() - 1] += item;
            }
            foreach (var item in list)
                Console.WriteLine(item);
            Console.Read();

Can anybody help me?