func main()
	var n: int :: cui@inputInt()
	var a: []int :: #[n]int
	for i(0, n - 1)
		do a[i] :: cui@inputInt()
	end for
	
	var posLast0: int :: -1
	var cntNon0: int :: 0
	for i(0, n - 1)
		if(a[i] = 0)
			do posLast0 :: i
		end if
		do cntNon0 :+ i - posLast0
	end for
	
	var ans: int :: n + n * (n - 1) / 2 - cntNon0
	do cui@print("\{ans}\n")
end func