2094 balanced girls-weak Edition

Description

We all know that the number of girls in these schools is different,
Now, the college-university community has made a decision that does not actually exist, that is, to balance the girls in these colleges and universities. The so-called balance means that the number of girls in these colleges is the same. This involves moving girls.
Girls move to another school. Moving a girl from one school to another consumes one unit,
Of course, moving y girls from one school to another requires a price of Y. Now we provide the number of girls in n colleges and universities. I hope you can calculate whether or not you can achieve this goal. If you can, what is the minimum price.

Input

Multiple groups of test data, each group of test data occupies two rows, the first row is an integer N (1 <= n <= 20), and the second row has n integers: A1, a2 ,..., AI ,..., an, indicating the number of girls in the n colleges. (AI> = 0, int In the int range)

Output

If the goal described in the question can be achieved, the minimum cost will be output. If not, output-1. For each group of test data, the output occupies one row.
The result is within the int range.

Sample Input

3

6 8 9

3

9 8 10

Sample output

-1 

 1 

 simulated question 

 
 # include 
      
        int main () {int N, I, sum, average; int A [101]; int answer; while (scanf ("% d", & N )! = EOF) {sum = 0; answer = 0; for (I = 0; I