Please subscribe to the official Codeforces channel in Telegram via the link: https://t.me/codeforces_official.
×

Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ACM-ICPC mode for virtual contests.
If you've seen these problems, a virtual contest is not for you - solve these problems in the archive.
If you just want to solve some problem from a contest, a virtual contest is not for you - solve this problem in the archive.
Never use someone else's code, read the tutorials or communicate with other person during a virtual contest.

No tag edit access

A. Array Without Local Maximums

time limit per test

2 secondsmemory limit per test

512 megabytesinput

standard inputoutput

standard outputIvan unexpectedly saw a present from one of his previous birthdays. It is array of $$$n$$$ numbers from $$$1$$$ to $$$200$$$. Array is old and some numbers are hard to read. Ivan remembers that for all elements at least one of its neighbours ls not less than it, more formally:

$$$a_{1} \le a_{2}$$$,

$$$a_{n} \le a_{n-1}$$$ and

$$$a_{i} \le max(a_{i-1}, \,\, a_{i+1})$$$ for all $$$i$$$ from $$$2$$$ to $$$n-1$$$.

Ivan does not remember the array and asks to find the number of ways to restore it. Restored elements also should be integers from $$$1$$$ to $$$200$$$. Since the number of ways can be big, print it modulo $$$998244353$$$.

Input

First line of input contains one integer $$$n$$$ ($$$2 \le n \le 10^{5}$$$) — size of the array.

Second line of input contains $$$n$$$ integers $$$a_{i}$$$ — elements of array. Either $$$a_{i} = -1$$$ or $$$1 \le a_{i} \le 200$$$. $$$a_{i} = -1$$$ means that $$$i$$$-th element can't be read.

Output

Print number of ways to restore the array modulo $$$998244353$$$.

Examples

Input

3

1 -1 2

Output

1

Input

2

-1 -1

Output

200

Note

In the first example, only possible value of $$$a_{2}$$$ is $$$2$$$.

In the second example, $$$a_{1} = a_{2}$$$ so there are $$$200$$$ different values because all restored elements should be integers between $$$1$$$ and $$$200$$$.

Codeforces (c) Copyright 2010-2018 Mike Mirzayanov

The only programming contests Web 2.0 platform

Server time: Dec/16/2018 03:37:29 (d1).

Desktop version, switch to mobile version.

Supported by

User lists

Name |
---|