You are given an array $a$ of $n$ positive integers and an integer $x$. You can do the following two-step operation any (possibly zero) number of times:
- Choose an index
$i$($1 \leq i \leq n$). - Increase
$a_i$by$x$, in other words$a_i := a_i + x$.
Find the maximum value of the $\operatorname{MEX}$ of $a$ if you perform the operations optimally.
The $\operatorname{MEX}$ (minimum excluded value) of an array is the smallest non-negative integer that is not in the array. For example:
- The
$\operatorname{MEX}$of$[2,2,1]$is$0$because$0$is not in the array. - The
$\operatorname{MEX}$of$[3,1,0,1]$is$2$because$0$and$1$are in the array but$2$is not. - The
$\operatorname{MEX}$of$[0,3,1,2]$is$4$because$0$,$1$,$2$and$3$are in the array but$4$is not.
Input
Each test contains multiple test cases. The first line contains the number of test cases $t$ ($1 \le t \le 5000$). The description of the test cases follows.
The first line of each test case contains two integers $n$ and $x$ ($1 \le n \le 2 \cdot 10^5$; $1 \le x \le 10^9$) — the length of the array and the integer to be used in the operation.
The second line of each test case contains $n$ integers $a_1, a_2, \ldots, a_n$ ($0 \le a_i \le 10^9$) — the given array.
It is guaranteed that the sum of $n$ over all test cases does not exceed $2 \cdot 10^5$.
Output
For each test case, output a single integer: the maximum $\operatorname{MEX}$ of $a$ if you perform the operations optimally.
Note
In the first test case, the $\operatorname{MEX}$ of $a$ is $4$ without performing any operations, which is the maximum.
In the second test case, the $\operatorname{MEX}$ of $a$ is $5$ without performing any operations. If we perform two operations both with $i=1$, we will have the array $a=[5,3,4,1,0,2]$. Then, the $\operatorname{MEX}$ of $a$ will become $6$, which is the maximum.
In the third test case, the $\operatorname{MEX}$ of $a$ is $0$ without performing any operations, which is the maximum.
样例
3
6 3
0 3 2 1 5 2
6 2
1 3 4 1 0 2
4 5
2 5 10 3
4
6
0
题面与样例版权归 Codeforces 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。