以2的个数构造前缀和
#include<bits/stdc++.h>
using namespace std;
#define int long long
#define LL long long
#define IOS ios::sync_with_stdio(false), cin.tie(0), cout.tie(0)
#define PII pair<int,int>
#define PLL pair<LL, LL>
#define VVI vector<vector<int>>
#define VI vector<int>
#define lowbit(x) ((x) & -(x))
#define fr front
#define ff first
#define ss second
#define pb push_back
#define PQ priority_queue<int>
const int N = 1010;
void solved() {
int n;
cin >> n;
int a[N] = {0};
for (int i = 1; i <= n; i ++ ) {
int x;
cin >> x;
if (x == 2) a[i] = 1;
}
for (int i = 1; i <= n; i ++ ) a[i] += a[i - 1];
for (int i = 1; i <= n; i ++ ) {
if (a[i] == a[n] - a[i]) {
cout << i << '\n';
return ;
}
}
cout << -1 << '\n';
return ;
}
signed main() {
IOS;
int t;
cin >> t;
while (t -- ) {
solved();
}
return 0;
}