# Input: lines like "<#>,<#>"
# Output: largest rectangle with corners at two such points
#         and fully within lines between adjacent points (last/first adjacent)

points = []

file = open("9_input.txt", "r")
for line in file:
  line = line.replace("\n", "")
  point_str = line.split(",")
  point = [int(point_str[0]), int(point_str[1])]
  points.append(point)

x_coords = []
y_coords = []

for point in points:
  if not (point[0] in x_coords):
    x_coords.append(point[0])
  if not (point[1] in y_coords):
    y_coords.append(point[1])

x_coords = sorted(x_coords)
y_coords = sorted(y_coords)

x_indices = {}
y_indices = {}

for index in range(0, len(x_coords)):
  x_indices[x_coords[index]] = 2 * index + 2
for index in range(0, len(y_coords)):
  y_indices[y_coords[index]] = 2 * index + 2

grid_size_x = 2 * len(x_coords) + 8
grid_size_y = 2 * len(y_coords) + 8

grid = []
for x_index in range(0, grid_size_x):
  row = []
  for y_index in range(0, grid_size_y):
    row.append("?")
  grid.append(row)

def fill_line(point, point2):
  min_x = min(point[0], point2[0])
  max_x = max(point[0], point2[0])
  min_y = min(point[1], point2[1])
  max_y = max(point[1], point2[1])
  for x_index in range(x_indices[min_x], x_indices[max_x] + 1):
    for y_index in range(y_indices[min_y], y_indices[max_y] + 1):
      grid[x_index][y_index] = "#"

for index in range(0, len(points) - 1):
  fill_line(points[index], points[index + 1])

fill_line(points[len(points) - 1], points[0])

grid[0][0] = "."

outside_points = [[0, 0]]

def flood_neighbors(outside_point):
  for dx in range(-1, 2):
    for dy in range(-1, 2):
      x = outside_point[0] + dx
      y = outside_point[1] + dy
      if 0 <= x < len(grid):
        if 0 <= y < len(grid[0]):
          if grid[x][y] == "?":
            outside_points.append([x, y])
            grid[x][y] = "."

while len(outside_points) > 0:
  outside_point = outside_points.pop(0)
  flood_neighbors(outside_point)

def is_filled(point, point2):
  min_x = min(point[0], point2[0])
  max_x = max(point[0], point2[0])
  min_y = min(point[1], point2[1])
  max_y = max(point[1], point2[1])
  for x_index in range(x_indices[min_x], x_indices[max_x] + 1):
    for y_index in range(y_indices[min_y], y_indices[max_y] + 1):
      if grid[x_index][y_index] == ".":
        return False
  return True

max_area = 0
for index in range(0, len(points) - 1):
  for index2 in range(index + 1, len(points)):
    point, point2 = points[index], points[index2]
    if is_filled(point, point2):
      area = (abs(point[0] - point2[0]) + 1) * (abs(point[1] - point2[1]) + 1)
      max_area = max(max_area, area)
print (max_area)