http://cur.lv/4x9e0 (Earn Bitcoins)

i = 0
write "How many levels? : "
a = read()
a = tonumber(a)
while i < a do
 turtle.digDown()
 turtle.down()
   while not turtle.forward() do
     turtle.dig()
   end
 turtle.digUp()
   while turtle.detectUp() do
     turtle.digUp()
   end
 while turtle.up()==false do
     turtle.digUp()
 end
 turtle.digUp()
 turtle.down()
 i = i+1
end
 if not turtle.back() then
   turtle.turnLeft()
   turtle.turnLeft()
   turtle.dig()
   turtle.forward()
  else
   turtle.turnLeft()
   turtle.turnLeft()
   turtle.forward()
 end
   while i>0 do
     turtle.up()
       while not turtle.forward() do
         turtle.dig()
       end
     i = i-1
   end
 turtle.turnLeft()
 turtle.turnLeft()