Problem Statement

You are given a sequence $A$ of length $N$ consisting of $0$ and $1$. The $i\ (1\leq i \leq N)$-th element of the sequence is $A_i$.

Find the number of pairs $(l,\ r)\ (1 \leq l \leq r \leq N)$ such that $\displaystyle \prod_{i=l}^{r}A_i = 0$.

Here,
$\displaystyle \prod_{i=l}^{r}A_i\ =\ A_l \times A_{l+1} \times \cdots \times A_{r}$
.

Constraints

• $1 \leq N \leq 2 \times 10^5$
• $A_i = 0,\ 1\ (1 \leq i \leq N)$
• All inputs are integers.

Input

$N$
$A_1\ A_2\ \cdots \ A_N$

Output

Output the answer, followed by a newline.

Sample

3
1 0 1

4

5
1 1 1 1 1

0

10
1 1 0 1 1 1 0 0 1 1

43