'''
Given an array A of n positive numbers. The task is to find the first Equilibium Point in the array. 
Equilibrium Point in an array is a position such that the sum of elements before it is equal to the sum of elements after it.

Example 1:

Input:
-------
n = 1
A[] = {1}

Output: 1

Explanation:
------------
Since its the only element hence
its the only equilibrium point.

Example 2:

Input:
-------
n = 5
A[] = {1,3,5,2,2}

Output: 3

Explanation:
------------
For second test case
equilibrium point is at position 3 
as elements before it (1+3) = 
elements after it (2+2).
 

Your Task:
-----------
The task is to complete the function equilibriumPoint() which takes the array and n as input parameters and returns the point of equilibrium.
Return -1 if no such point exists.

Expected Time Complexity: O(n)
Expected Auxiliary Space: O(1)

Constraints:
1 <= n <= 106
1 <= A[i] <= 108

'''
class Solution:
    def equilibriumPoint(self,A,N):
        if N == 1:
            return 1
        l_sum = 0
        t_sum = sum(A)
        for i in range(N):
            t_sum -= A[i]
            if l_sum == t_sum:
                return i + 1
            l_sum += A[i]
        return -1

if __name__ == '__main__':
    T = int(input())
    while T > 0:
        N = int(input())
        A = [int(x) for x in input().split()]
        ob = Solution()
        print(ob.equilibriumPoint(A,N))
        T -= 1

