import Control.Applicative
import Control.Monad

main :: IO ()
main = do
  [h, w] <- f
  solve [h, w] <$> replicateM h getLine >>= print
  where
    f = map read <$> words <$> getLine

solve :: [Int] -> [String] -> Double
solve [h, w] pss = minimum $ do
  (rx, ry) <- rs
  return $ sum $ do
    (bx, by) <- bs
    return $ dist (rx, ry) (bx, by)
  where
    rs = map (\x -> (x, 0)) [1..w] ++ map (\x -> (x,h+1)) [1..w]
         ++ map (\y -> (0, y)) [1..h] ++ map (\y -> (w+1,y)) [1..h]
    bs :: [(Int, Int)]
    bs = do
      (y, s) <- zip [1..] pss
      (x, c) <- zip [1..] s
      guard $ c == '1'
      return (x, y)

dist :: (Int, Int) -> (Int, Int) -> Double
dist (x0, y0) (x1, y1) = sqrt $ (fromIntegral dx) ^ 2 + (fromIntegral dy) ^ 2
  where
    dx = abs (x0 - x1)
    dy = abs (y0 - y1)