miner

function dlr()
  turtle.turnLeft()
  turtle.dig()
  turtle.turnRight()
  turtle.turnRight()
  turtle.dig()
  turtle.turnLeft()
end

function digup()
  if turtle.detectUp() then
    turtle.digUp()
    digup()
  else
    turtle.up()
  end
end

function digdown()
  if turtle.detectDown() then
    turtle.digDown()
    digdown()
  else
    turtle.down()
  end
end

function forward()
  if turtle.detect() then
    turtle.dig()
    forward()
  else
    turtle.forward()
  end
end

function loop()
  dlr()
  digup()
  dlr()
  digup()
  dlr()
  forward()
  dlr()
  digdown()
  dlr()
  digdown()
  dlr()
  forward()
end

write("How far should I mine? length = n*2 \n")
local Num = tonumber( read() )
for i=1,Num do
  loop()
  if i % 2 == 0 then
    turtle.turnLeft()
    turtle.turnLeft()
    turtle.select(16)
    turtle.place()
    turtle.turnLeft()
    turtle.turnLeft()
  end
end