func main()
	var s: []char :: cui@input()
	var ans: bool :: true
	for i(0, ^s - 1)
		if(i % 2 = 0)
			if(s[i] = ' ')
				do ans :: false
			end if
		else
			if(s[i] <> ' ')
				do ans :: false
			end if
		end if
	end for
	do cui@print(ans ?("Yes\n", "No\n"))
end func