def f(ar,dx,dy,h,w,c)
	
	arr= Marshal.load(Marshal.dump(ar))

	return false if c==0
	h.times{|y|
		
		w.times{|x|
			y1=y+dy
			x1=x+dx
			if arr[y][x]==1
				return false if x1<0 || x1>=w || y1<0 || y1>=h
				arr[y1][x1]-=1
				c-=2
			end
			next if x1<0 || x1>=w ||  y1<0 || y1>=h
			return false if arr[y1][x1]<0
		}
	}
	return c==0
end

h,w=gets.split.map{|e| e.to_i}
m=[]
h.times{
	m<<gets.chomp
}


arr=Array.new(h).map{Array.new(w,0)}
c=0
i=0
m.each{|e|
	j=0
	e.chars{|e2|
		if e2=="#"
			arr[i][j]=1
			c+=1
		else
			arr[i][j]=0
		end
		j+=1
	}
	i+=1
}

ok=false
h.times{|dy|
	w.times{|dx|
		if dy+dx!=0
			ok=ok||f(arr,dx,dy,h,w,c)
			ok=ok||f(arr,-dx,dy,h,w,c)
		end
	}
}
if ok==true
	puts "YES"
else
	puts "NO"
end