Bits at Crossroads

using System;

class Crossroads
{
    static void Main()
    {
        int sizeOfBoard = int.Parse(Console.ReadLine());
        int[,] matrix = new int[sizeOfBoard, sizeOfBoard];

        string input = Console.ReadLine();
        int crossroads = 0;
        while (input != "end")
        {
            string[] predefinedCrossroad = input.Split(' ');
            int line = int.Parse(predefinedCrossroad[0]);
            int position = int.Parse(predefinedCrossroad[1]);
            if (line == 0 || line == sizeOfBoard - 1 || position == 0 || position == sizeOfBoard - 1)
            {
                crossroads++; // predefined crossroad which will not be detected in the scan later.
            }
            int col = position;
            int row = line;

            while (col >= 0 && row <= sizeOfBoard - 1) // filling the matrix to bottom right
            {

                matrix[row, col] = 1;
                row++;
                col--;
            }
            col = position;
            row = line;
            while (col <= sizeOfBoard - 1 && row >= 0) // filling the matrix to upper left
            {
                matrix[row, col] = 1;
                row--;
                col++;
            }
            col = position;
            row = line;
            while (col >= 0 && row >= 0) // filling the matrix to upper right
            {
                matrix[row, col] = 1;
                row--;
                col--;

            }
            col = position;
            row = line;
            while (col <= sizeOfBoard - 1 && row <= sizeOfBoard - 1) // filling to bottom left
            {
                matrix[row, col] = 1;
                row++;
                col++;
            }
            input = Console.ReadLine();

        }
        string binary = "";
        long integer = 0;
        for (int row = 0; row <= sizeOfBoard - 1; row++)
        {
            for (int col = sizeOfBoard - 1; col >= 0; col--)
            {

                binary += matrix[row, col]; // getting the string representation of the binary number
                if ((row > 0 && row < sizeOfBoard - 1) && (col > 0 && col < sizeOfBoard - 1))
                {
                    if (matrix[row, col] == 1 && matrix[row + 1, col + 1] == 1 && matrix[row - 1, col + 1] == 1 && matrix[row + 1, col - 1] == 1 && matrix[row - 1, col - 1] == 1)
                    {
                        crossroads++; // checking for a crossroad
                    }
                }



            }
            Console.WriteLine(integer = Convert.ToInt64(binary, 2)); // binary to integer

            binary = ""; // getting the binary again to default value because otherwise all numbers will stack.

        }
        Console.WriteLine(crossroads);

    }
}