Farming turtle

--Program pro farmici zelvu pro farmareni
--Verze programu beta 0.9.6
--vytvoril SVty
--*****************************
term.clear()
term.setCursorPos(1,1)
print("Tento program slouzi pro farmareni")
print("Osivo rozlozte do slotu jedna az ctyri")
print("--------------------")
print("Napiste delku farmy:")
delka = (read())
print("Delka farmy je "..delka.. " kostek")
print("Zadejte sirku farmy:")
sir = (read())
print("Sirka farmy je "..sir.." kostek")
sir = sir /2
sem = true
slot = 1
rada = 0
sleep(1)

function palivo()
  if (turtle.getFuelLevel()) < 20 then
    turtle.select(16)
    turtle.refuel(1)
    turtle.select(slot)
    print("Doplnuji palivo")
  end
end

palivo()
if (turtle.detectDown()) then
  turtle.up()
  turtle.dig()
  turtle.forward()
else
  turtle.dig()
  turtle.forward()
end

function left()
turtle.turnLeft()
turtle.dig()
turtle.forward()
turtle.turnLeft()
turtle.dig()
turtle.forward()
end

function right()
turtle.turnRight()
turtle.dig()
turtle.forward()
turtle.turnRight()
turtle.dig()
turtle.forward()
end

function farm()
  rada = rada + 1
  turtle.select(slot)
  for i=1,delka do
    if sem == true then
      if turtle.getItemCount(slot) == 1 then
        slot = slot + 1
        if slot == 5 then
          slot = 1
          print("Nedostatek osiva!")
          sem = false
        end
        turtle.select(slot)
      end
    else
      turtle.select(1)
      print("Pouze okopavam")
    end
      turtle.dig()
      turtle.digDown()
      turtle.digDown()
      if turtle.getItemCount(slot) > 1 then
        turtle.placeDown()
      end
      palivo()
      turtle.forward()
    end
    print(rada)
end

function retu()
  sir = sir *2
  turtle.turnLeft()
  turtle.turnLeft()
  turtle.forward()
  turtle.turnRight()
  for c=1,sir do
    turtle.forward()
  end
  turtle.turnRight()
end

--program
for d=1,sir do
  farm()
  right()
  farm()
  left()
end
--program

retu()
print("HOTOVO")