using System;

using System.IO;

​

public class Program

{

    public static void Main()

    {

          try

            {

                string filename = Environment.GetFolderPath(Environment.SpecialFolder.DesktopDirectory) + "\\input.txt";

                int[,] inputTriangle = readInput(filename);

​

                if (inputTriangle != null)

                {

                    int posSolutions = (int)Math.Pow(2, inputTriangle.GetLength(0) - 1);

                    int largestSum = 0;

                    int tempSum, index;

​

                    int lines = inputTriangle.GetLength(0);

​

​

                    for (int i = 0; i <= posSolutions; i++)

                    {

                        tempSum = inputTriangle[0, 0];

                        index = 0;

                        for (int j = 0; j < inputTriangle.GetLength(0) - 1; j++)

                        {

                            index = index + (i >> j & 1);

                            tempSum += inputTriangle[j + 1, index];

                        }

​

                        if (tempSum > largestSum)

                        {

                            largestSum = tempSum;

                        }

                    }

                    Console.WriteLine("The largest sum through the triangle is: {0}", largestSum);

                }

            }

            catch (Exception e)

            {

                Console.WriteLine("Please enter your input in correct format!");

            }

    }

     private static int[,] readInput(string filename)

        {

            string line;

            string[] linePieces;

            int lines = 0;

​

            StreamReader r = new StreamReader(filename);

            while ((line = r.ReadLine()) != null)

            {

                lines++;

            }

​

            int[,] inputTriangle = new int[lines, lines];

            r.BaseStream.Seek(0, SeekOrigin.Begin);

​

            int j = 0;

            while ((line = r.ReadLine()) != null)

            {

                linePieces = line.Split(' ');

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

                {

                    if (isPrime(int.Parse(linePieces[i])))

                    {

                        inputTriangle[j, i] = 0;

                    }

                    else

                    {

                        inputTriangle[j, i] = int.Parse(linePieces[i]);

                    }

                }

                j++;

            }

            r.Close();

            return inputTriangle;

        }

        public static bool isPrime(int number)

        {

            if (number == 1) return false;

            if (number == 2) return true;

​

            var boundary = (int)Math.Floor(Math.Sqrt(number));

​

            for (int i = 2; i <= boundary; ++i)

            {

                if (number % i == 0) return false;

            }

            return true;

        }

}