{-# OPTIONS_GHC -O2 #-}
{-# LANGUAGE BangPatterns, BinaryLiterals, CPP, DerivingStrategies  #-}
{-# LANGUAGE DerivingVia, FlexibleContexts, FlexibleInstances       #-}
{-# LANGUAGE GeneralizedNewtypeDeriving, KindSignatures, LambdaCase #-}
{-# LANGUAGE MagicHash, MultiParamTypeClasses, MultiWayIf           #-}
{-# LANGUAGE NumericUnderscores, OverloadedStrings, PatternSynonyms #-}
{-# LANGUAGE RankNTypes, RecordWildCards, ScopedTypeVariables       #-}
{-# LANGUAGE StandaloneDeriving, TupleSections, TypeApplications    #-}
{-# LANGUAGE TypeFamilies, TypeInType, UnboxedTuples, ViewPatterns  #-}

import           Control.Applicative
import           Control.Exception
import           Control.Monad
import           Control.Monad.Primitive
import           Control.Monad.Reader
import           Control.Monad.ST
import           Control.Monad.State.Strict
import           Data.Bifunctor
import           Data.Bool
import qualified Data.ByteString                   as B
import qualified Data.ByteString.Builder           as B
import qualified Data.ByteString.Char8             as C
import qualified Data.ByteString.Internal          as B
import qualified Data.ByteString.Unsafe            as B
import           Data.Char
import qualified Data.Foldable                     as F
import           Data.Function
import           Data.Functor.Identity
import qualified Data.IntMap.Strict                as IM
import qualified Data.IntSet                       as IS
import qualified Data.List                         as L
import qualified Data.Map.Strict                   as M
import           Data.Monoid
import           Data.Ord
import           Data.Primitive
import           Data.Proxy
import           Data.Ratio
import           Data.Semigroup
import qualified Data.Set                          as S
import           Data.Tuple
import qualified Data.Vector                       as V
import qualified Data.Vector.Algorithms.Intro      as Intro
import qualified Data.Vector.Fusion.Stream.Monadic as MS
import qualified Data.Vector.Fusion.Bundle.Monadic as MB
import           Data.Vector.Fusion.Util
import qualified Data.Vector.Generic               as G
import qualified Data.Vector.Generic.Mutable       as GM
import qualified Data.Vector.Mutable               as VM
import qualified Data.Vector.Primitive             as P
import qualified Data.Vector.Primitive.Mutable     as PM
import qualified Data.Vector.Unboxed               as U
import qualified Data.Vector.Unboxed.Mutable       as UM
import           Debug.Trace
import           Foreign                           hiding (void)
import           GHC.Exts
import           GHC.TypeLits
import           System.IO
import           Unsafe.Coerce

#define MOD 1000000007

main :: IO ()
main = do
    [n, m] <- map read.words <$> getLine
    cs <- U.unfoldrN (n*m) (runParser char) . C.filter (not.isSpace) <$> C.getContents
    case solve n m cs of
        (mf, mat) -> do
            print mf
            forM_ [0..n-1] $ \i -> do
                putStrLn . U.toList $ U.slice (i * m) m mat

solve :: Int -> Int -> U.Vector Char -> (Int, U.Vector Char)
solve h w mat = second answer $ bipartiteMatching (h * w) $ \builder -> do
    rep h $ \i -> do
        rep w $ \j -> when (mat U.! ix i j == '.') $ do
            neighbor4 i j $ \ni nj -> when (inGrid h w ni nj && mat U.! ix ni nj == '.') $ do
                addEdgeBMB (ix i j) (ix ni nj) builder
    return ()
  where
    ix i j = i * w + j
    {-# INLINE ix #-}

    answer :: U.Vector Int -> U.Vector Char
    answer m = flip U.imap m $ \xy xy' ->
        if xy' == nothingBM
        then mat U.! xy
        else let (x, y) = quotRem xy w
                 (x', y') = quotRem xy' w
             in case (x' - x, y' - y) of
                    (1, 0) -> 'v'
                    (-1,0) -> '^'
                    (0, 1) -> '>'
                    (0, -1) -> '<'

inGrid :: Int -> Int -> Int -> Int -> Bool
inGrid h w x y = 0 <= x && x < h && 0 <= y && y < w
{-# INLINE inGrid #-}

neighbor4 :: (Applicative f) => Int -> Int -> (Int -> Int -> f ()) -> f ()
neighbor4 x y f = f (x - 1) y *> f x (y - 1) *> f x (y + 1) *> f (x + 1) y
{-# INLINE neighbor4 #-}


type Vertex = Int

bipartiteMatching
    :: Int -- ^ number of vertices
    -> (forall s . BipartiteMatchingBuilder s -> ST s ()) -> (Int, U.Vector Vertex)
bipartiteMatching n run = runST $ do
    builder <- newBipartiteMatchingBuilder n
    run builder
    bm <- buildBipartiteMatching builder
    m <- runBipartiteMatching bm
    (,) m <$> U.freeze (matchBM bm)

data BipartiteMatching s = BipartiteMatching
    { numVerticesBM :: !Int
    , matchBM       :: !(UM.MVector s Int)
    , usedBM        :: !(UM.MVector s Bool)
    , offsetBM      :: !(U.Vector Int)
    , adjacentBM    :: !(U.Vector Int)
    }

nothingBM :: Int
nothingBM = -1
{-# INLINE nothingBM #-}

dfsBM :: (PrimMonad m) => BipartiteMatching (PrimState m) -> Vertex -> (Bool -> m ()) -> m ()
dfsBM BipartiteMatching{..} = dfs
  where
    dfs !v k = UM.unsafeRead usedBM v >>= \case
        True -> k False
        False -> do
            UM.unsafeWrite usedBM v True
            let begin = U.unsafeIndex offsetBM v
            let end = U.unsafeIndex offsetBM (v + 1)
            flip fix begin $ \loop !i -> do
                if i < end
                then do
                    let nv = U.unsafeIndex adjacentBM i
                    mnv <- UM.unsafeRead matchBM nv
                    if mnv == nothingBM
                    then do
                        UM.unsafeWrite matchBM v nv
                        UM.unsafeWrite matchBM nv v
                        k True
                    else do
                        dfs mnv $ \case
                            True -> do
                                UM.unsafeWrite matchBM v nv
                                UM.unsafeWrite matchBM nv v
                                k True
                            False -> loop (i + 1)
                else k False
{-# INLINE dfsBM #-}

runBipartiteMatching :: (PrimMonad m)
    => BipartiteMatching (PrimState m) -> m Int
runBipartiteMatching bm@BipartiteMatching{..} = do
    res <- UM.replicate 1 0
    updated <- UM.replicate 1 True
    fix $ \loop -> do
        UM.unsafeWrite updated 0 False
        rep numVerticesBM $ \i -> do
            mi <- UM.unsafeRead matchBM i
            when (mi == nothingBM) $ do
                dfsBM bm i $ \case
                    True -> do
                        UM.unsafeWrite updated 0 True
                        UM.unsafeModify res (+1) 0
                    False -> return ()
        UM.unsafeRead updated 0 >>= \case
            True -> do
                UM.set usedBM False
                loop
            False -> UM.unsafeRead res 0
{-# INLINE runBipartiteMatching #-}

data BipartiteMatchingBuilder s = BipartiteMatchingBuilder
    { numVerticesBMB :: !Int
    , inDegreeBMB    :: UM.MVector s Int
    , edgesBMB       :: VecStack s (Vertex, Vertex)
    }

newBipartiteMatchingBuilder :: (PrimMonad m)
    => Int -> m (BipartiteMatchingBuilder (PrimState m))
newBipartiteMatchingBuilder n = BipartiteMatchingBuilder n
    <$> UM.replicate n 0
    <*> newVecStack (1024 * 1024)

addEdgeBMB :: (PrimMonad m)
    => Vertex -> Vertex -> BipartiteMatchingBuilder (PrimState m) -> m ()
addEdgeBMB !src !dst BipartiteMatchingBuilder{..} = do
    UM.unsafeModify inDegreeBMB (+1) src
    pushVS (src, dst) edgesBMB
{-# INLINE addEdgeBMB #-}

buildBipartiteMatching :: (PrimMonad m)
    => BipartiteMatchingBuilder (PrimState m)
    ->  m (BipartiteMatching (PrimState m))
buildBipartiteMatching BipartiteMatchingBuilder{..} = do
    let numVerticesBM = numVerticesBMB
    matchBM <- UM.replicate numVerticesBM nothingBM
    usedBM <- UM.replicate numVerticesBM False
    offsetBM <- U.scanl' (+) 0 <$!> U.unsafeFreeze inDegreeBMB
    madjacentBM <- UM.unsafeNew (U.last offsetBM)
    moffset <- U.thaw offsetBM
    edges <- freezeVecStack edgesBMB
    U.forM_ edges $ \(src, dst) -> do
        offset <- UM.unsafeRead moffset src
        UM.unsafeWrite moffset src (offset + 1)
        UM.unsafeWrite madjacentBM offset dst
    adjacentBM <- U.unsafeFreeze madjacentBM
    return BipartiteMatching{..}
{-# INLINE buildBipartiteMatching #-}

-------------------------------------------------------------------------------
-- Utils
-------------------------------------------------------------------------------
rep :: (Monad m) => Int -> (Int -> m ()) -> m ()
rep n = flip MS.mapM_ (stream 0 n)
{-# INLINE rep #-}
rev :: (Monad m) => Int -> (Int -> m ()) -> m ()
rev !n = flip MS.mapM_ (streamR 0 n)
{-# INLINE rev #-}
stream :: (Monad m) => Int -> Int -> MS.Stream m Int
stream !l !r = MS.Stream step l where { step x | x < r = return $ MS.Yield x (x + 1) | otherwise = return MS.Done; {-# INLINE [0] step #-}}
{-# INLINE [1] stream #-}
streamR :: (Monad m) => Int -> Int -> MS.Stream m Int
streamR !l !r = MS.Stream step (r - 1) where { step x | x >= l = return $ MS.Yield x (x - 1) | otherwise = return MS.Done; {-# INLINE [0] step #-}}
{-# INLINE [1] streamR #-}
stream' :: (Monad m) => Int -> Int -> Int -> MS.Stream m Int
stream' !l !r !d = MS.Stream step l where { step x | x < r = return $ MS.Yield x (x + d) | otherwise = return MS.Done; {-# INLINE [0] step #-}}
{-# INLINE [1] stream' #-}
infixl 8 `shiftRL`, `unsafeShiftRL`
shiftRL :: Int -> Int -> Int
shiftRL = unsafeShiftRL
{-# INLINE shiftRL #-}
unsafeShiftRL :: Int -> Int -> Int
unsafeShiftRL (I# x#) (I# i#) = I# (uncheckedIShiftRL# x# i#)
{-# INLINE unsafeShiftRL #-}
type Parser a = StateT C.ByteString Maybe a
runParser :: Parser a -> C.ByteString -> Maybe (a, C.ByteString)
runParser = runStateT
{-# INLINE runParser #-}
int :: Parser Int
int = coerce $ C.readInt . C.dropWhile isSpace
{-# INLINE int #-}
int1 :: Parser Int
int1 = fmap (subtract 1) int
{-# INLINE int1 #-}
char :: Parser Char
char = coerce C.uncons
{-# INLINE char #-}
byte :: Parser Word8
byte = coerce B.uncons
{-# INLINE byte #-}
skipSpaces :: Parser ()
skipSpaces = modify' (C.dropWhile isSpace)
{-# INLINE skipSpaces #-}
lowerBoundM :: (Monad m) => Int -> Int -> (Int -> m Bool) -> m Int
lowerBoundM low high p = go low high where { go !low !high | high <= low = return high | otherwise = p mid >>= bool (go (mid + 1) high) (go low mid) where { mid = low + unsafeShiftRL (high - low) 1}}
{-# INLINE lowerBoundM #-}
upperBoundM :: (Monad m) => Int -> Int -> (Int -> m Bool) -> m Int
upperBoundM low high p = do { flg <- p high; if flg then return high else subtract 1 <$!> lowerBoundM low high (fmap not . p)}
{-# INLINE upperBoundM #-}
lowerBound :: Int -> Int -> (Int -> Bool) -> Int
lowerBound low high p = runIdentity (lowerBoundM low high (return . p))
{-# INLINE lowerBound #-}
upperBound :: Int -> Int -> (Int -> Bool) -> Int
upperBound low high p = runIdentity (upperBoundM low high (return . p))
{-# INLINE upperBound #-}
-------------------------------------------------------------------------------
-- Data.VecStack
-------------------------------------------------------------------------------
data VecStack s a = VecStack{intVarsVS :: !(UM.MVector s Int), internalVecStack :: !(UM.MVector s a)}
_sizeVS :: Int
_sizeVS = 0
{-# INLINE _sizeVS #-}
newVecStack :: (PrimMonad m, UM.Unbox a) => Int -> m (VecStack (PrimState m) a)
newVecStack n = VecStack <$> UM.replicate 1 0 <*> UM.unsafeNew n
defaultVecStackSize :: Int
defaultVecStackSize = 1024 * 1024
popVS :: (PrimMonad m, UM.Unbox a) => VecStack (PrimState m) a -> m (Maybe a)
popVS (VecStack info s) = do { len <- UM.unsafeRead info _sizeVS; if len > 0 then do { UM.unsafeWrite info _sizeVS (len - 1); pure <$> UM.unsafeRead s (len - 1)} else return Nothing}
{-# INLINE popVS #-}
pushVS :: (PrimMonad m, UM.Unbox a) => a -> VecStack (PrimState m) a -> m ()
pushVS x (VecStack info s) = do { len <- UM.unsafeRead info _sizeVS; UM.unsafeWrite s len x; UM.unsafeWrite info _sizeVS (len + 1)}
{-# INLINE pushVS #-}
pushesVS :: (PrimMonad m, UM.Unbox a) => U.Vector a -> VecStack (PrimState m) a -> m ()
pushesVS vec (VecStack info s) = do { len <- UM.unsafeRead info _sizeVS; UM.unsafeWrite info _sizeVS (len + U.length vec); U.unsafeCopy (UM.unsafeSlice len (U.length vec) s) vec}
{-# INLINE pushesVS #-}
freezeVecStack :: (PrimMonad m, U.Unbox a) => VecStack (PrimState m) a -> m (U.Vector a)
freezeVecStack (VecStack info s) = do { l <- UM.unsafeRead info _sizeVS; U.unsafeFreeze $ UM.take l s}
{-# INLINE freezeVecStack #-}
