local facingDirs = {{x=0, z=1}, {x=-1, z=0}, {x=0, z=-1},  {x=1, z=0}}
local facingIdx = 0
pos = {x=0, y=0, z=0}

local getFacing = function()
    return facingDirs[facingIdx + 1]
end

local repeatN = function(ct, fn)
    for i=1, ct do
        if not fn() then
            return false
        end
    end

    return true
end

local splitToInt = function(inputstr, sep)
    if sep == nil then
            sep = "%s"
    end
    local t={}
    for str in string.gmatch(inputstr, "([^"..sep.."]+)") do
            table.insert(t, tonumber(str))
    end
    return t
end

getFuelLevel = function()
    return (turtle.getItemCount(1)-1) * 80 + turtle.getFuelLevel()
end

forward = function()
    while needFuel() do
        if turtle.getItemCount(1) >= 1 then
            turtle.select(1)
            turtle.refuel(1)
        else
            os.sleep(3)
            print("i need fuel! ", getFuelLevel())
        end
    end

    local b, reason = turtle.forward()
    if not b then
        print("failed,", reason)
        return false
    end

    local facing = getFacing()
    pos.x = pos.x + facing.x
    pos.z = pos.z + facing.z

    print("coords", pos.x, pos.y, pos.z)
    print("fuel", getFuelLevel())

    return true
end

up = function()
    if not turtle.up() then
        return false
    end
    pos.y = pos.y + 1

    return true
end

down = function()
    if not turtle.down() then
        return false
    end
    pos.y = pos.y - 1

    return true
end

forwardDig = function()
    turtle.dig()
    return forward()
end

forwardFullDig = function()
    if not forwardDig() then
        return false
    end

    turtle.digUp()
    turtle.digDown()

    return true
end

turnLeft = function()
    facingIdx = (facingIdx - 1) % 4
    turtle.turnLeft()
end

turnRight = function()
    facingIdx = (facingIdx + 1) % 4
    turtle.turnRight()
end

local findDirIdx = function(idx)
    -- created from truth table
    if facingIdx-1 == idx or (facingIdx == 0 and idx == 3) then
        while facingIdx ~= idx do
            turnLeft()
        end
    else
        while facingIdx ~= idx do
            turnRight()
        end
    end
end

getFreeInventorySlotsCount = function()
    local total = 0
    for i = 1, 16 do
        if turtle.getItemCount(i) == 0 then
            total = total + 1
        end
    end
    return total
end

depositInventoryForward = function()
    for i = 2, 16 do
        turtle.select(i)
        turtle.drop()
    end
end

goToRelativeCoords = function(x, y, z, o_fn)
    local fn = o_fn == nil and forward or o_fn

    local desiredXDir = pos.x > x and 1 or 3
    local desiredZDir = pos.z > z and 2 or 0

    while pos.x ~= x or pos.y ~= y or pos.z ~= z do
        if pos.x ~= x then
            findDirIdx(desiredXDir)
            while pos.x ~= x and fn() do end
        end
        if pos.z ~= z then
            findDirIdx(desiredZDir)
            while pos.z ~= z and fn() do end
        end
        while pos.y < y and up() do end
        while pos.y > y and down() do end
    end
end

needFuel = function() return getFuelLevel() <= (math.abs(pos.x) + math.abs(pos.y) + math.abs(pos.z) + 40) or turtle.getFuelLevel() <= 0 end

goHomeAndDeposit = function()
    goToRelativeCoords(0, 0, 0)
    findDirIdx(2)
    depositInventoryForward()
end

forwardFullDigWithAttention = function()

    if not forwardFullDig() then
        return false
    end

    if getFreeInventorySlotsCount() <= 1 then
        local oldFacingIdx = facingIdx
        local oldPos = {x=pos.x, y=pos.y, z=pos.z}

        goHomeAndDeposit()

        goToRelativeCoords(oldPos.x, oldPos.y, oldPos.z)
        findDirIdx(oldFacingIdx)
    end

    return true
end

digRectangleOld = function(x, y, z, w, h)
    goToRelativeCoords(x, y, z, forwardFullDigWithAttention)
    for i=0, math.floor(w/2) do
        local j = i*2
        goToRelativeCoords(x + j, y, z + h, forwardFullDigWithAttention)
        if (j+1 >= w) then
            return
        end
        goToRelativeCoords(x + j+1, y, z + h, forwardFullDigWithAttention)
        goToRelativeCoords(x + j+1, y, z, forwardFullDigWithAttention)
        if (j+2 >= w) then
            return
        end
        goToRelativeCoords(x + j+2, y, z, forwardFullDigWithAttention)
    end
end

digRectangle = function(x1, y1, z1, x2, y2, z2)
    goToRelativeCoords(x1, y1, z1)
    for gx = 0, x2-x1 do
        for pz = 0, z2-z1 do
            local gz = pz

            if gx % 2 == 1 then
                gz = z2-z1 - pz
            end
            goToRelativeCoords(x1+gx, 0, z1+gz, forwardFullDigWithAttention)
        end
    end
end

buildFunction = function(w, h, f)
    for x = 0, w do
        for py = 0, h do
            local y = py
            if x % 2 == 1 then
                y = h - py
            end

            print(math.floor(f(x, y)))
            goToRelativeCoords(x, math.floor(f(x, y)), y)
            for i = 1, 16 do
                turtle.select(i)
                if turtle.placeUp() then
                    break
                end
            end
        end
    end
end

findDirIdx(0)

while true do
    local func = loadstring(io.read())
    setfenv(func, getfenv())
    turtle.refuel(1)
    func()
    goHomeAndDeposit()
end