using System;

using System.Text.RegularExpressions;

using System.Linq;

public class Program

{

    public static void Main()

    {

        string input = "0ut5yst3m5";        

        Console.WriteLine(string.Format("Sum without loop = {0}", SumWithoutLoop(input)));

        Console.WriteLine(string.Format("Sum with loop = {0}", SumWithLoop(input)));

    }

    public static int SumWithoutLoop(string input)

    {

        string inputNumericOnly = Regex.Replace(input, "[^.0-9]", "");

        return inputNumericOnly.Select(x => int.Parse(x.ToString())).Sum();;

    }

    public static int SumWithLoop(string input)

    {

        int sum = 0;

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

        {

            char ch = input[i];

            if (char.IsDigit(ch))

            {

                sum += Int32.Parse(ch.ToString());

            }

        }

        return sum;

    }

}