function check(H,W,x,y,s)
  
  if x < W && s[x+1][y] == '#'
    return true
  end
  
  if x > 1 && s[x-1][y] == '#'
    return true
  end
  
  if y < H && s[x][y+1] == '#'
    return true
  end
  
  if y > 1 && s[x][y-1] == '#'
    return true
  end
  
  return false
  
end

function main()
  
  (H,W) = map(x -> parse(Int,x), split(readline()))
  s = chomp.(readlines())
  
  ans_check = false
  
  for i in 1:H
    for j in 1:W
      
      if s[i][j] == '#' && !check(H,W,i,j,s)
        ans_check = true
        break
      end
      
    end
  end
  
  if ans_check
    println("No")
  else
    println("Yes")
  end
  
end

main()