length = 30
x = 0

function checkfuel()
 if turtle.getfuellevel() < 10 then
  turtle.select(16)
  turtle.refuel(1)
  turtle.select(1)
 end
end

function strip()
 checkfuel()
 turtle.dig()
 turtle.forward()
 turtle.digup()
end

function turnaround()
 turtle.turnleft()
 strip()
 strip()
 strip()
 turtle.turnleft()
end

checkfuel()
for x = 1, length do
 strip()
end

turnaround()
x = 0

for x = 1, length do
 strip()
end