require "table2"

local width  = 75
local height = 52
local max_steps = 12000

enum begin white = 0, black end
enum begin up = 0, right, down, left end

local x = width // 2
local y = height // 2
local m = table.create(height)
for i = 1, height do m[i] = table.rep(width, 0) end
local dir = up
local i = 0
while i < max_steps and 0 <= x < width and 0 <= y < height do
    local turn = (m[y + 1][x + 1] == black)
    dir = (dir + (turn ? 1 : -1)) & 3
    m[y + 1][x + 1] = (m[y + 1][x + 1] == black) ? white : black
    if dir == up then
        y -= 1
    elseif dir == right then
        x -= 1
    elseif dir == down then
        y += 1
    else
        x += 1
    end
    i += 1
end
for j = 1, height do
    for k = 1, width do io.write((m[j][k] == white) ? "." : "#") end
    print()
end