Let's call a sequence of integers $$$x_1, x_2, \dots, x_k$$$ MEX-correct if for all $$$i$$$ ($$$1 \le i \le k$$$) $$$|x_i - \operatorname{MEX}(x_1, x_2, \dots, x_i)| \le 1$$$ holds. Where $$$\operatorname{MEX}(x_1, \dots, x_k)$$$ is the minimum non-negative integer that doesn't belong to the set $$$x_1, \dots, x_k$$$. For example, $$$\operatorname{MEX}(1, 0, 1, 3) = 2$$$ and $$$\operatorname{MEX}(2, 1, 5) = 0$$$.
You are given an array $$$a$$$ consisting of $$$n$$$ non-negative integers. Calculate the number of non-empty MEX-correct subsequences of a given array. The number of subsequences can be very large, so print it modulo $$$998244353$$$.
Note: a subsequence of an array $$$a$$$ is a sequence $$$[a_{i_1}, a_{i_2}, \dots, a_{i_m}]$$$ meeting the constraints $$$1 \le i_1 < i_2 < \dots < i_m \le n$$$. If two different ways to choose the sequence of indices $$$[i_1, i_2, \dots, i_m]$$$ yield the same subsequence, the resulting subsequence should be counted twice (i. e. two subsequences are different if their sequences of indices $$$[i_1, i_2, \dots, i_m]$$$ are not the same).
The first line contains a single integer $$$t$$$ ($$$1 \le t \le 10^5$$$) — the number of test cases.
The first line of each test case contains a single integer $$$n$$$ ($$$1 \le n \le 5 \cdot 10^5$$$).
The second line contains $$$n$$$ integers $$$a_1, a_2, \dots, a_n$$$ ($$$0 \le a_i \le n$$$).
The sum of $$$n$$$ over all test cases doesn't exceed $$$5 \cdot 10^5$$$.
For each test case, print a single integer — the number of non-empty MEX-correct subsequences of a given array, taken modulo $$$998244353$$$.
4 3 0 2 1 2 1 0 5 0 0 0 0 0 4 0 1 2 3
4 2 31 7
In the first example, the valid subsequences are $$$[0]$$$, $$$[1]$$$, $$$[0,1]$$$ and $$$[0,2]$$$.
In the second example, the valid subsequences are $$$[0]$$$ and $$$[1]$$$.
In the third example, any non-empty subsequence is valid.
