using System;

using System.IO;

​

class Program

{

    static void Main()

    {

        // Read the pyramid input from a file

        string[] lines = File.ReadAllLines("input.txt");

        int rows = lines.Length;

        int[][] pyramid = new int[rows][];

​

        // Fill the pyramid array

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

        {

            string[] values = lines[i].Split(' ');

            pyramid[i] = new int[values.Length];

            for (int j = 0; j < values.Length; j++)

            {

                pyramid[i][j] = int.Parse(values[j]);

            }

        }

​

        // Process the pyramid to find the maximum sum avoiding primes

        for (int row = rows - 2; row >= 0; row--) // Start from the second last row

        {

            for (int col = 0; col < pyramid[row].Length; col++)

            {

                if (IsPrime(pyramid[row][col]))

                    continue;

​

                // Choose the maximum valid adjacent element from the row below

                int down = (row + 1 < rows && col < pyramid[row + 1].Length && !IsPrime(pyramid[row + 1][col])) ? pyramid[row + 1][col] : 0;

                int diagonal = (row + 1 < rows && col + 1 < pyramid[row + 1].Length && !IsPrime(pyramid[row + 1][col + 1])) ? pyramid[row + 1][col + 1] : 0;

​

                pyramid[row][col] += Math.Max(down, diagonal); // Add the maximum path sum

            }

        }

​

        // The result will be at the top of the pyramid

        Console.WriteLine("Maximum sum path: " + pyramid[0][0]);

    }

​

    // Helper function to check if a number is prime

    static bool IsPrime(int number)

    {

        if (number <= 1) return false;

        for (int i = 2; i <= Math.Sqrt(number); i++)

        {

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

        }

        return true;

    }

}

​