-- VARIABLE(s)

n1 = 0

-- FUNCTION(s)

function refuel(gas)
	if turtle.getFuelLevel() < gas then
		for r = 1, 16 do
			if turtle.getItemCount(r) > 0 then
				turtle.select(r)
				repeat
					if not turtle.refuel(1) then
						return
					end
				until turtle.getFuelLevel() > gas or turtle.getItemCount == 0
			end
		end
	end
end


-- CODE

if not turtle.dig() then
	return print("error. tree not detected")
end

refuel(1)
turtle.forward()

if not turtle.detect() then
	tree = 1
end

if tree ~= 1 then
	turtle.turnLeft()
	if turtle.detect() then
		tree = "left"
	end
	turtle.turnRight()
	if tree ~= "left" then
		turtle.turnRight()
		if turtle.detect() then 
			tree = "right"
		end
		turtle.turnLeft()
	end
end

while turtle.digUp() do
	if tree ~= 1 then
		turtle.dig()
	end
	refuel(10)
	turtle.up()
	n1 = n1+1
end

if tree == "left" then
	turtle.turnLeft()
	turtle.dig()
	turtle.forward()
	turtle.turnRight()
elseif tree == "right" then
	turtle.turnRight()
	turtle.dig()
	turtle.forward()
	turtle.turnLeft()
else
	refuel(n1)
	for i = n1,1,-1 do
		turtle.down()
	end
	return print("DONE!")
end

for i = n1,1,-1 do
	turtle.digDown()
	turtle.dig()
	refuel(10)
	turtle.down()
	turtle.dig()
end
print("DONE")