One and Two

You are given a sequence $a\_1, a\_2, \ldots, a\_n$. Each element of $a$ is $1$ or $2$.

Find out if an integer $k$ exists so that the following conditions are met.

• $1 \leq k \leq n-1$, and
• $a\_1 \cdot a\_2 \cdot \ldots \cdot a\_k = a\_{k+1} \cdot a\_{k+2} \cdot \ldots \cdot a\_n$.

If there exist multiple $k$ that satisfy the given condition, print the smallest.

Each test contains multiple test cases. The first line contains the number of test cases $t$ ($1 \le t \le 100$). Description of the test cases follows.

The first line of each test case contains one integer $n$ ($2 \leq n \leq 1000$).

The second line of each test case contains $n$ integers $a\_1, a\_2, \ldots, a\_n$ ($1 \leq a\_i \leq 2$).

For each test case, if there is no such $k$, print $-1$.

Otherwise, print the smallest possible $k$.