dy = [-1,0,1,0]
dx = [0,1,0,-1]

h,w = parse.(Int64,split(readline()))
s = []

for i in 1:h
  line = split(readline())
  for j in line
    push!(s,j)
  end
end

res = 1

for i in 1:h
  for j in 1:w
    if s[i][j] == '#'
      _res = 0
      for k in 1:4
        ny = i + dy[k]
        nx = j + dx[k]
        if ny < 1 || ny > h || nx < 1 || nx > w
          continue
        end
        if s[ny][nx] == '#'
          _res = 1
          break
        end
      end

      if _res == 0
        global res = 0
        break
      end
    end

    if res == 0
      break
    end
  end

  if res == 0
    break
  end
end

println( res == 1 ? "Yes" : "No")