using System.Text;

​

namespace EnumsDemo

{

    public class Program

    {

        public static void Main(string[] args)

        {

            Console.WriteLine(sorting("1BbccCaA432"));

        }

​

        public static string sorting(string str)

        {

            var col = str.ToCharArray().AsEnumerable();

            StringBuilder sb = new StringBuilder();

​

            sb.Append(col

                .Where(a => !char.IsNumber(a))

                .OrderBy(a => char.ToLower(a))

                //.OrderByDescending(a => char.ToLower(a)) 

                .ThenBy(a => char.IsUpper(a))

                .ToArray());

​

            sb.Append(col

                .Where(a => char.IsNumber(a))

                .Where(a => a % 2 == 0)

                .OrderBy(a => a)

                .ToArray());

​

            var sb2 = sb.ToString().ToList().ForEach(a => a.Where(a % 2 == 0));    

​

            //for (int i = 0; i < sb.Length; i++)

            //{

            //    if (i % 2 != 0)

            //    {

            //        sb2 += sb[i];

            //    }

            //}

​

            return sb.ToString(); 

        }

    }

}