parseInt(x) = parse(Int, x)

function isblack(x::Array{String, 2}, i, j, h, w)
	if i > h || j > w || i < 1 || j < 1
		return(0)
	elseif x[i,j] == "#"
		return(1)
	else
		return(0)
	end
end

function isolate(x::Array{String, 2}, i,j, h, w)
	if isblack(x, i-1, j, h, w)+isblack(x, i+1, j, h, w)+isblack(x, i, j-1, h, w)+isblack(x, i, j+1, h, w) == 0
		return(1)
	else
		return(0)
	end
end

function main()
	h, w = parseInt.(split(readline()))
	s = Array{String}(h,w)
	for i in 1:h
		s[i,:] = split(chomp(readline()))
	end
	flg = 0
	for i in 1:h
		for j in 1:w
			if s[i,j] == "#"
				if isolate(s, i, j, h, w) == 1
					print("No")
					flg = 1
					break
				end
			end
		end
		if flg == 1
			break
		end
	end
	if flg == 0
		print("Yes")
	end
end

main()