Trust Nobody

Description:

Input:

The first line contains a single integer $$$t$$$ ($$$1 \leq t \leq 1000$$$) — the number of test cases.

The first line of each test case contains a single integer $$$n$$$ ($$$1 \leq n \leq 100$$$).

The second line of each test case contains $$$n$$$ integers $$$l_i$$$ ($$$0 \leq l_i \leq n$$$) — the number said by the $$$i$$$-th person.

It's guaranteed that the sum of all $$$n$$$ does not exceed $$$10^4$$$.

Output:

For each test case output a single integer. If what people are saying is contradictory, output $$$-1$$$. Otherwise, output the number of liars in the group. If there are multiple possible answers, output any one of them.

Sample Input:

7
2
1 2
2
2 2
2
0 0
1
1
1
0
5
5 5 3 3 5
6
5 3 6 6 3 5

Sample Output:

1
-1
0
-1
0
3
4

Note:

In the first example, the only possible answer is that the second person is a liar, so the answer is $$$1$$$ liar.

In the second example, it can be proven that we can't choose the liars so that all the requirements are satisfied.

In the third example, everybody tells the truth, so the answer is $$$0$$$ liars.