def square(surface, x, y, edge_length, displacement_statement):
    displacement = eval(displacement_statement)
    height_sum = 0
    for dx in [-edge_length // 2, edge_length // 2]:
        for dy in [-edge_length // 2, edge_length // 2]:
            height_sum += surface[x + dx, y + dy]
    height_average = height_sum / 4
    surface[x, y] = height_average + displacement


def diamond(surface, x, y, edge_length, displacement_statement):
    dimension = len(surface)
    displacement = eval(displacement_statement)
    height_sum = 0
    points_count = 0
    for dx in [-edge_length // 2, 0, edge_length // 2]:
        for dy in [-edge_length // 2, 0, edge_length // 2]:
            if (dx == 0 or dy == 0) and not (dx == 0 and dy == 0):
                if 0 <= x + dx < dimension and 0 <= y + dy < dimension:
                    height_sum += surface[x + dx, y + dy]
                    points_count += 1
                elif not 0 <= x + dx < dimension:
                    height_sum -= surface[x - dx, y + dy]
                    points_count -= 1
                else:
                    height_sum -= surface[x + dx, y - dy]
                    points_count -= 1
    height_average = height_sum / points_count
    surface[x, y] = height_average + displacement


def main():
    surfaces = []
    dimension = 2**dimension_exponent + 1
    surface = numpy.zeros((dimension, dimension))
    surface[0, 0] = bottom_left
    surface[dimension - 1, 0] = bottom_right
    surface[0, dimension - 1] = top_left
    surface[dimension - 1, dimension - 1] = top_right
    edge_length = dimension - 1
    surfaces.append(surface[::edge_length, ::edge_length].copy())
    while edge_length > 1:
        # Square step
        for x in range(edge_length // 2, dimension - 1, edge_length):
            for y in range(edge_length // 2, dimension - 1, edge_length):
                square(surface, x, y, edge_length, displacement_statement)
        # Diamond step
        for x in range(edge_length // 2, dimension - 1, edge_length):
            for y in range(edge_length // 2, dimension - 1, edge_length):
                diamond(surface, x - edge_length //2, y, edge_length, displacement_statement)
                diamond(surface, x, y - edge_length // 2, edge_length, displacement_statement)
        for x in range(edge_length // 2, dimension - 1, edge_length):
            diamond(surface, x, dimension - 1, edge_length, displacement_statement)
        for y in range(edge_length // 2, dimension - 1, edge_length):
            diamond(surface, dimension - 1, y, edge_length, displacement_statement)
        surfaces.append(surface[::(edge_length // 2), ::(edge_length // 2)].copy())
        edge_length = edge_length // 2