function dig()
 turtle.digUp()
 turtle.digDown()
 turtle.dig()
end

function left()
 turtle.turnLeft()
 dig()
 turtle.forward()
 turtle.turnLeft()
end

function right()
 turtle.turnRight()
 dig()
 turtle.forward()
 turtle.turnRight()
end

turn = false

for j=1,5 do
 for i=1,9 do
  turtle.refuel(1)
  dig()
  turtle.forward()
 end
 if turn == false then
  turn = true;
  left()
 else if turn == true then
  turn = false;
  right()
 end
end