module Main where

import Control.Monad
ok :: (Int,Int) -> (Int,Int) -> [[Char]] -> Bool
ok (x,y) (h,w) s =
    (s !! y !! x == '.') || (((x == 0) && (y == 0)) || (if x == 0
                                                       then s !! (y-1) !! x == '.'
                                                       else if y == 0
                                                           then s !! y !! (x-1) == '.'
                                                           else s !! (y-1) !! (x-1) == '.'))

main :: IO ()
main = do
    [h,w] <- (map read . words) <$> getLine
    s <- replicateM h  <$> getLine
    if and [and [ok (i,j) (h,w) s | i <- [0..w-1]] | j <- [0..h-1]]
            then putStrLn "Yes"
            else putStrLn "No"
    return()