tunnel

function gravelCheck()
  while turtle.detect() do
    turtle.dig()
  end
end
function leftTunnel()
  turtle.turnLeft()
  for i=1, 5 do
    turtle.dig()
    if turtle.detect then
      gravelCheck()
    else
    turtle.forward()
    end
    turtle.digUp()
  end
  for i=1, 5 do
    turtle.back()
  end
  turtle.turnRight()
end
write("")
print("How long")
x = read()
local torch = 0
local digLeft = 0
for i=1, x do
  torch = torch + 1
  digLeft = digLeft + 1
  if digLeft == 4 then
   leftTunnel()
   digLeft=0
  end
  if torch == 10 then
    turtle.select(16)
    turtle.turnRight()
    turtle.placeUp()
    turtle.turnLeft()
    torch=0
  end
  turtle.dig()
  if turtle.detect() then
    gravelCheck()
  else
  turtle.forward()
  end
  turtle.digUp()
end
for i=1, x do
  turtle.back()
end