print("ok")
local origin = {0,0,0}
local max = {72,2,144}
local dir = 0;
local modX = {0,1,0,-1}
local modZ = {-1,0,1,0}
local location = {0,0,0}

function turnAround()
right()
right()
end

function right()
  dir = dir + 1 % 4
end



function left()
  dir = dir - 1
  if dir < 0 then
    dir = 0
  end
end

function down(dig)
  while true do
    if turtle.down() then
      break
    end
    if turtle.detectDown() then
      if dig then
        turtle.digDown()
      end
    end
    sleep(0)
  end
  location[1]=location[1]-1
end

function up(dig)
  while true do
    if turtle.up() then
      break
    end
    if dig then
      if turtle.detectUp() then
        turtle.digUp()
      end
    end
  sleep(0)
  end
  location[2] = location[2] + 1
end
function forward(dig)
  while true do
    if turtle.forward() then
      break
    end
    if turtle.detect() then
      if dig then
        turtle.dig()
      end
    end
    sleep(0)
  end
  location[1] = location[1] + modX[dir];
  location[3] = location[3] + modZ[dir];
end

function back(dig)
  while true do
    if turtle.back() then
      break
    end
    if dig then
      turnAround()
      if turlte.detect() then
        turtle.dig()
      end
      turnAround()
    end
    sleep(0)
  end
  location[1] = location[1]+modX[dir];
  location[3] = location[3]+modZ[dir];
end

function getLocCopy()
  local copy = {}
  for i,n in ipairs(location) do
    copy[i]=n
  end
  return copy;
end

function checkInventory()
  if turtle.getItemCount(9) > 0 then
    return true
   end
   return false
end

function dropOff(x,y,z)
  local org = getLocCopy()
  if z%2 == 1 then
    left()
    forward(false)
    right()
  end
  while dir~=2 do
    left()
    sleep(0)
  end
  while location[3] ~= origin[3] do
    forward(false)
    sleep(0)
  end
  if location[1] ~= origin[1] then
    local left = false
    if location[1] <0 then
      left()
      left = true
    elseif location[1]>0 then
      right()
    end
    while location[1] ~= origin[1] do
      forward(false)
      sleep(0)
    end

    if left then
     right()
    else
      left()
    end

  end
  forward(false)
  forward(false)
  dropAll()
  turnAround()
  forward(false)
  forward(false)

  if left then
    left()
  else
    right()
  end
  while location[1] ~= org[1] do
      forward(false)
      sleep(0)
  end

  if left then
    right()
  else
    left()
  end
  if org[3] % 2 == 1 then
    right()
    forward(false)
    left()
  end
  while location[3]~=org[3] do
    forward(false)
    sleep(0)
  end
  if org[3]%2==1 then
    left()
    forward(true)
    right()

  end

end

function dropAll()
  for i=1,9,1 do
    turtle.select(i)
    if turtle.getItemCount(i) >0 then
      turtle.drop(turtle.getItemCount(i));
    end
  end

end

local input = ""
while input ~= "start" do
  input = io.read()
  sleep(0)
end

local location = {0,0,0}

  for x=0,max[1],1 do
    for z=0,max[3],1 do
      for y=1,max[2],1 do

        up(true);
        checkInventory()
        down(false);
      end
      forward(true);
      checkInventory()
    end
    left()
    forward(true)
    left()
    back(true)
  end