using System;

     public class MainClass

    {

          static bool isPrime(int num) {

           if (num <= 1) {

               return false;

           }

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

               if (num % i == 0) {

                   return false;

               }

           }

           return true;

    }

        public static void Main (string[] args)

        {

            string input = @"1

                             8 4

                             2 6 9

                             8 5 9 3";

            var charArray = input.Split ('\n');

            int num= charArray.Length;

            int[,] list = new int[num,num+1];

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

                var numArr = charArray[i].Trim().Split(' ');

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

                {

                    int number = Convert.ToInt32 (numArr[j]);

                    list [i, j] = number;

                }

            }

            for(int i=0; i<num; i++){

                for(int j=0;j<num; j++){

                    if(isPrime(list[i,j]))

                        list[i,j]=0;

                }

            }

            for (int i = num-2; i >= 0; i--) {

                for (int j = 0; j < num; j++) {

                    list[i,j] = Math.Max(list[i, j] + list[i+1, j], list[i,j] + list[i+1, j+1]);

                }

            }

            Console.WriteLine ( list[0,0]);

        }

    }

​