Description:
Allen has an array $$$a_1, a_2,\ldots,a_n$$$. For every positive integer $$$k$$$ that is a divisor of $$$n$$$, Allen does the following:
- He partitions the array into $$$\frac{n}{k}$$$ disjoint subarrays of length $$$k$$$. In other words, he partitions the array into the following subarrays: $$$$$$[a_1,a_2,\ldots,a_k],[a_{k+1}, a_{k+2},\ldots,a_{2k}],\ldots,[a_{n-k+1},a_{n-k+2},\ldots,a_{n}]$$$$$$
- Allen earns one point if there exists some positive integer $$$m$$$ ($$$m \geq 2$$$) such that if he replaces every element in the array with its remainder when divided by $$$m$$$, then all subarrays will be identical.
Help Allen find the number of points he will earn.
Input Format:
Each test consists of multiple test cases. The first line contains a single integer $$$t$$$ ($$$1 \leq t \leq 10^4$$$) — the number of test cases. The description of the test cases follows.
The first line of each test case contains a single integer $$$n$$$ ($$$1 \leq n \leq 2\cdot10^5$$$) — the length of the array $$$a$$$.
The second line of each test case contains $$$n$$$ integers $$$a_1, a_2,\ldots, a_n$$$ ($$$1 \leq a_i \leq n$$$) — the elements of the array $$$a$$$.
It is guaranteed that the sum of $$$n$$$ over all test cases does not exceed $$$2 \cdot 10^5$$$.
Output Format:
For each test case, output a single integer — the number of points Allen will earn.
Note:
In the first test case, $$$k=2$$$ earns a point since Allen can pick $$$m = 2$$$ and both subarrays will be equal to $$$[1, 0]$$$. $$$k=4$$$ also earns a point, since no matter what $$$m$$$ Allen chooses, there will be only one subarray and thus all subarrays are equal.
In the second test case, Allen earns $$$1$$$ point for $$$k=3$$$, where his choice for $$$m$$$ does not matter.