Solve the programming task below in a Python markdown code block.
Read problems statements in [Hindi], [Mandarin Chinese], [Russian], [Vietnamese], and [Bengali] as well.

Teams $A$ and $B$ are having a penalty shoot-out to decide the winner of their football match. Each team gets to take a shot $N$ times, and the team with the higher number of scored goals at the end wins. If the number of goals scored during the shoot-out by each team turns out to be the same even after all $2N$ shots, then they stop and agree that the result is a draw.

The two teams take shots alternately — team $A$ shoots first, then team $B$ shoots, then team $A$ and so on until team $B$ takes its $N$-th shot (at which point each team has taken exactly $N$ shots). Even though all $2N$ shots are taken, the result of the shoot-out is often known earlier — e.g. if team $A$ has already scored $N-1$ goals and team $B$ has missed at least two shots, team $A$ is definitely the winner.

For each shot, you know whether it was a goal or a miss. You need to find the earliest moment when the winner is known — the smallest $s$ ($0 ≤ s ≤ 2N$) such that after $s$ shots, the result of the shoot-out (whether team $A$ won, team $B$ won or the match is drawn) would be known even if we did not know the results of the remaining $2N-s$ shots.

------  Input ------
The first line of the input contains a single integer $T$ denoting the number of test cases. The description of $T$ test cases follows.
The first line of each test case contains a single integer $N$.
The second line contains a string $S$ with length $2 \cdot N$, where for each valid $i$, the $i$-th character is '0' if the $i$-th shot was a miss or '1' if it was a goal.

------  Output ------
For each test case, print a single line containing one integer — the smallest $s$ such that after $s$ shots, the result of the shoot-out is known.

------  Constraints ------
$1 ≤ T ≤ 10^{5}$
$1 ≤ N ≤ 10^{5}$
$S$ contains only characters '0' and '1'
the sum of $N$ over all test cases does not exceed $10^{6}$

----- Sample Input 1 ------ 
2

3

101011

3

100001
----- Sample Output 1 ------ 
4

6
----- explanation 1 ------ 
Example case 1: After four shots, team $A$ has scored $2$ goals and team $B$ has scored $0$ goals. Whatever happens afterwards, team $A$ is guaranteed to win, since even if team $B$ scored their last (and only) goal and team $A$ did not score their last goal, team $A$ would still win by $1$ goal.

Example case 2: Team $A$ scores the first goal and after that, neither team scores any goals until the last shot. Up till then, there is always a possibility that the match could end in a draw if team $B$ scored a goal with its last shot, or in the victory of team $A$ if it was a miss. We can only guarantee the result after the last shot.