local args = { ... }
if #args ~= 1 then
  print( "Usage: program <distance>" )
  error()
end

function moveForward()
 repeat
   turtle.dig()
 until turtle.forward()
end

function moveUp()
 repeat
   turtle.digUp()
 until turtle.up()
end

function moveDown()
 repeat
   turtle.digDown()
 until turtle.down()
end


function iterate(k)
  for j=1, k do
    moveUp()
  end
  moveForward()
  for j=1, k do
    moveDown()
  end
  moveForward()
end

length = args[1]
for i=1, length do
  turtle.select(1)
  turtle.refuel()
  iterate(5)
end
turtle.turnLeft()
iterate(1)
turtle.turnLeft()
for i=1, length do
  turtle.select(1)
  turtle.refuel()
  iterate(5)
end