Quarry - Engineering turtle

local block = 1
local quarry = 13
local tesseract = 16
local landmark = 15
local chest = 14
local length = 10
local height = 0


function height()
    term.clear()
    term.setCursorPos(1,1)
    print("Do you wish the turtle to setup the quarry in air?")
    print("Press Y/N to confirm")
    local event, key = os.pullEvent("key")
        if key == keys.y then
                print("How far up?")
                input = read()
            if input then
                height = tonumber(input)
            end
    return
end
end


function checkFuel()
    term.clear()
    term.setCursorPos(1,1)
    print("Checking if i have enough fuel..")
    sleep(2)

    if turtle.getFuelLevel() >= 500 then
        print("Im fine on fuel thanks.. press enter to continue.")
            while true do
                local event, key = os.pullEvent("key")
                if key == keys.enter then
            return
    elseif turtle.getFuelLevel() < 500 then
     print("Please give me fuel master!")
      if key == keys.enter then
        turtle.refuel()
     end

 end
   end
    end
end

function lenght()
    term.clear()
    term.setCursorPos(1,1)
    print("How big do you want the quarry?")
    input = read()
        if input then
            length = input
            elseif input == nil then
            print("Error..")
        end

    print("You have said that you want the quarry to be: ".. tostring(length))
    print("Are you sure?")
    print("Press Y/N")

        while true do
        local event, key = os.pullEvent("key")
            if key == keys.y then
                print("I'm gonna go a head and build you quarry!")
                sleep(2)
                Quarry()
            end
        if key == keys.n then
    print("You pressed N, breaking the program..")
    break
    end
  end
 end

function Quarry()
    for i = 0, height do
    turtle.up()
end

-- [ Landmarks ] --
    for i = 1,length do
        turtle.forward()
    end
    turtle.select(block)
    turtle.forward()
    turtle.placeDown()
    turtle.back()

    turtle.select(landmark)
    turtle.place()

    for o = 1, length -1  do
        turtle.back()
    end

    turtle.turnRight()

    for p = 1,length do
        turtle.forward()
    end

    turtle.select(block)
    turtle.forward()
    turtle.placeDown()
    turtle.back()
    turtle.select(landmark)
    turtle.place()

    for a = 1, length do
        turtle.back()
    end

    turtle.turnLeft()
    turtle.select(block)
    turtle.placeDown()
    turtle.back()
    turtle.select(landmark)
    turtle.place()
    turtle.attack()
-- [ Landmarks end] --
    turtle.back()
    turtle.select(quarry)
    turtle.place()
    turtle.up()
    turtle.select(chest)
    turtle.place()
    turtle.back()
    turtle.down()
    turtle.select(tesseract)
    turtle.place()
    print("Done.")
    for i = 0, height do
        turtle.down()
    end
  end

    function itemsSlot()
        term.clear()
        term.setCursorPos(1,1)
        print("Place following items in slot:")
        print("Block for air placement: 1")
        print("Quarry: 13")
        print("Chest: 14")
        print("Landmarks: 15")
        print("Tesseract: 16")
        sleep(10)
    end
-- [Main program] --

itemsSlot()
checkFuel()
height()
lenght()