using System;

public class Program

{

    public static void Main()

    {

         int[,] triangle = { {1, 0, 0 , 0},

                            {8, 4, 0 , 0},

                            {2, 6, 9 , 0},

                            {8 , 5 , 9 , 3}};

            Console.Write(maxSum(triangle, 3));

    }

    static int maxSum(int[,] tri, int x)

        {

            removePrime(ref tri);

​

            for (int i = x - 1; i >= 0; i--)

            {

​

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

                {

                    if (tri[i + 1, j] >

                           tri[i + 1, j + 1])

                        tri[i, j] +=

                               tri[i + 1, j];

                    else

                        tri[i, j] +=

                           tri[i + 1, j + 1];

                }

            }

​

            return tri[0, 0];

        }

        public static bool IsPrime(int integer)

        {

            if (integer <= 1) {

                return false;

                    }

            if (integer== 2)

            {

                return true;

            }

            if (integer % 2 == 0)

            {

                return false;

            }

​

            for (int i = 3; i <= (int)Math.Floor(Math.Sqrt(integer)); i += 2)

                if (integer % i == 0)

                    return false;

​

            return true;

        }

        private static void removePrime(ref int[,] TriangleMatrix)

        {

            for (int i = 0; i < TriangleMatrix.GetLength(0); i++)

            {

                for (int j = 0; j < TriangleMatrix.GetLength(0); j++)

                {

                    if (TriangleMatrix[i, j] == 0)

                    {

                        continue;

                    }

                    else if (IsPrime(TriangleMatrix[i, j]))       

                    {

                        TriangleMatrix[i, j] = 0;

                    }

                }

            }

        }

}