using System;

using System.Collections.Generic;

using System.Linq;

​

internal class Program

{

    private static void Main(string[] args)

    {

        List<List<int>> arrays = new List<List<int>>();

        string filePath = "D:\\projects\\pi_works\\PiWorks\\input.in"; // please insert your own file path here

​

        // Reading input line by line

        // while ((line = Console.ReadLine()) != null)

        foreach(var line in System.IO.File.ReadLines(filePath))

        {

            // Parse the line into a list of integers and add to the 2D list

            if (line == "" || line.Length == 0) break;

            var row = line.Split()

                          .Select(int.Parse)

                          .ToList();

            arrays.Add(row);

        }

​

        // Compute the maximum number

        int result = FindMaxNum(arrays);

​

        Console.WriteLine($"Maximum Path Sum: {result}");

    }

​

    private static int FindMaxNum(List<List<int>> arrayinput)

    {

        // Create a deep copy to avoid modifying the original input

        List<List<int>> arrayCopy = arrayinput.Select(innerList => new List<int>(innerList)).ToList();

        int N = arrayCopy.Count;

​

        // Iterate from the second-to-last row up to the top

        for (int i = N - 2; i >= 0; i--)

        {

            for (int k = 0; k < arrayCopy[i].Count; k++)

            {

                // Skip prime numbers

                if (IsPrime(arrayCopy[i][k]))

                {

                    continue;

                }

​

                // Safely calculate left diagonal, directly under, and right diagonal

                int leftDiag = (k - 1 >= 0) ? arrayCopy[i + 1][k - 1] : 0;

                int under = arrayCopy[i + 1][k];

                int rightDiag = (k + 1 < arrayCopy[i + 1].Count) ? arrayCopy[i + 1][k + 1] : 0;

​

                // Update the current cell with the maximum path sum

                arrayCopy[i][k] += Math.Max(leftDiag, Math.Max(under, rightDiag));

            }

        }

​

        // Return the top-left value as the result

        return arrayCopy[0][0];

    }

​

    private static bool IsPrime(int num)

    {

        if (num < 2) return false;

        for (int i = 2; i * i <= num; i++)

        {

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

        }

        return true;

    }

}

​