w,h = gets.split.map(&:to_i)
s = []

h.times do
  k = gets.chomp.split('')
  s << k
end
arr = Array.new(h+2){Array.new(w+2,0)}
x = [1,0,-1,0]
y = [0,1,0,-1]
(0...h).each do |i|
  (0...w).each do |j|
    if s[i][j] == '#'
      arr[i+1][j+1] = 1
    end
  end
end
(0...h).each do |i|
  (0...w).each do |j|
    if s[i][j] == '#'
      check = 0
      4.times do |k|
        dx = x[k]
        dy = y[k]
      	check += 1 if arr[(i+1)+dy][(j+1)+dx] == 1
      end
      if check == 0
        puts :No
        exit
      end
    end
  end
end

puts :Yes