/// <summary>
        /// Provjeri da li je ćelija za 2 mjesta od trenutne ćelije broj ili puna. Ako je -> zacrni ćeliju između njih.
        /// </summary>
        /// <param name="row"></param>
        /// <param name="column"></param>
        private void CheckNeighboursHorizontalAndVertical(int row, int column)
        {
            if ((row - 2) >= 0)
            {
                if (solver.CellIsNumber((row - 2), column) || solver.CellIsFull((row - 2), column))
                {
                    solver.UpdateCell((row - 1), column, 'B', -1);
                }
            }
            if ((row + 2) < solver.gridHeight)
            {
                if (solver.CellIsNumber((row + 2), column) || solver.CellIsFull((row + 2), column))
                {
                    solver.UpdateCell((row + 1), column, 'B', -1);
                }
            }

            if ((column - 2) >= 0)
            {
                if (solver.CellIsNumber(row, (column - 2)) || solver.CellIsFull(row, (column - 2)))
                {
                    solver.UpdateCell(row, (column - 1), 'B', -1);
                }
            }
            if ((column + 2) < solver.gridWidth)
            {
                if (solver.CellIsNumber(row, (column + 2)) || solver.CellIsFull(row, (column + 2)))
                {
                    solver.UpdateCell(row, (column + 1), 'B', -1);
                }
            }
        }