import Data.List
import Control.Monad

main = do
    (h:w:_) <- (fmap read . words) <$> getLine
    matrix <- replicateM h getLine
    let checkH = and $ map outHori matrix
    let matrixT = transpose matrix
    let checkV = and $ map outHori matrixT
    if (checkH && checkV)
        then print "Yes"
        else print "No"


outHori :: String -> Bool
outHori str = (take 2 str == "#.") || isInfixOf ".#." str || (drop ((length str)-2) str == ".#")
