local a1,a2,a3 = ...

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

function forward()
  turtle.dig()
  while ( !turtle.forward() ) do
    turtle.dig()
  end
end

function turn( d )
  if ( d == 0 ) then
    turtle.turnLeft()
  else
    turtle.turnRight()
  end
end

dir = a1
for a=1,a2 do
  column()
  for b=1,a3 do
    column()
    forward()
  end
  column()
  turn(dir)
  forward()
  column()
  turn(dir)
  dir=1-dir
end