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CF1538B.Friends and Candies
Friends and Candies
Polycarp has friends, the -th of his friends has candies. Polycarp's friends do not like when they have different numbers of candies. In other words they want all to be the same. To solve this, Polycarp performs the following set of actions exactly once:
- Polycarp chooses () arbitrary friends (let's say he chooses friends with indices );
- Polycarp distributes their candies among all friends. During distribution for each of candies he chooses new owner. That can be any of friends. Note, that any candy can be given to the person, who has owned that candy before the distribution process.
Note that the number is not fixed in advance and can be arbitrary. Your task is to find the minimum value of .
For example, if and , then Polycarp could make the following distribution of the candies:
- Polycarp chooses friends with indices and distributes candies to make (two candies go to person ).
Note that in this example Polycarp cannot choose friend so that he can redistribute candies so that in the end all are equal.
For the data and , determine the minimum value . With this value , Polycarp should be able to select friends and redistribute their candies so that everyone will end up with the same number of candies.
Input
The first line contains one integer (). Then test cases follow.
The first line of each test case contains one integer ().
The second line contains integers ().
It is guaranteed that the sum of over all test cases does not exceed .
Output
For each test case output:
- the minimum value of , such that Polycarp can choose exactly friends so that he can redistribute the candies in the desired way;
- "
-1" if no such value exists.
Samples
5
4
4 5 2 5
2
0 4
5
10 8 5 1 4
1
10000
7
1 1 1 1 1 1 1
2
1
-1
0
0
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