SOLVE

LATER

Equal Array

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You are given an array \(A \)** **of size \(N\)

Find the minimum non negative number \(X\) such that there exist an index \(j\)** **and when you can replace** \(A_j\) by \(A_j+X\),** the sum of elements of array from index \(1 \)** to \(j\)** ** **and **\(j+1\)** **to ** \(N\) becomes equal, where **\(1 \le j \le N-1\)**. Assume array to be **1-indexed**.

If there is no possible \(X\) print **\(-1\)** in separate line.

**Input Format**

The first line contains \(T\), the number of test cases.

**For each Test case :**

The first line contains an integer \(N\), size of the array.

The second line contains \(N\)** **space-separated integers, the \(i^{th}\) of which is \(A_i\).

**Input Constraints**

\( 1 \le T \le 10^{ 5} \)

\( 2 \le N \le 10^{5} \)

\( 0 \le A_i \le 10^{6} \)

Sum of N all over testcases doesn't not exceed \(10^{6}\).

**Output Format**

For each test case, print the required answer in separate line.

Explanation

Add \(3\) to the \(2^{nd}\)index(1-indexing).

Time Limit:
1.0 sec(s)
for each input file.

Memory Limit:
256 MB

Source Limit:
1024 KB