Solve the programming task below in a Python markdown code block.
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Chef has an array A of length N.

Since Chef's favorite number is 3, he wants to make all numbers in the array a multiple of 3.

Chef can do the following operation:
Select any 2 different indices i and j and increase A_{i} by 1 and decrease A_{j} by 1.

Help Chef find out the minimum number of operations required (or report its not possible) to achieve his objective.

------ Input Format ------ 

- The first line will contain T, the number of test cases. Then the test cases follow.
- The first line of each test case contains N, denoting the length of the array.
- The second line of each testcase contains N space separated integers A_{i}.

------ Output Format ------ 

Output the minimum number of operations required to make all numbers divisible by 3.

If it is not possible to make every number divisible by 3, then output -1.

------ Constraints ------ 

$1 ≤ T ≤ 1000$
$2 ≤ N ≤ 10^{5}$
$1 ≤ A_{i} ≤ 10^{9}$
- Sum of $N$ over all test cases does not exceed $2 \cdot 10^{5}$

----- Sample Input 1 ------ 
3
3
1 2 3
4
6 3 9 12
2
4 3

----- Sample Output 1 ------ 
1
0
-1

----- explanation 1 ------ 
Test Case $1$: Chef can select the indices $2$ and $1$ and thus increase $A_{2}$ by $1$ and decrease $A_{1}$ by $1$. Thus the array becomes $[0,3,3]$. So every number is now divisible by $3$.

Test Case $2$: Since all the numbers are already multiples of $3$, Chef will not need to apply the operation at all.

Test Case $3$: There is no way to make all the numbers a multiple of $3$.