#include <bits/stdc++.h>
#define MAX 100
using namespace std;
long long TimKiemNhiPhan(vector <long long> arr, long long l, long long r, long long x){
    if(r >= l){
        long long mid = (l+r)/2;
        if(arr[mid] == x){
            return mid+1;
        }
        if(arr[mid] > x){
            return TimKiemNhiPhan(arr, l, mid-1, x);
        }
        return TimKiemNhiPhan(arr, mid+1, r, x);
    }
    return -1;
}
int main(){
    int t; cin >> t;
    while(t--){
        long long n; cin >> n;
        vector<long long> arr;

        for(long long i = 0; i < n; i++){
            long long temp; cin >> temp;
            arr.push_back(temp);
        }
        vector<long long> arr2 = arr;
        for(long long i = 0; i < n - 1; i++){
            long long temp2; cin >> temp2;
            arr.erase(remove(arr.begin(), arr.end(), temp2),arr.end());
        }
        long long diff = arr[0];
        cout << TimKiemNhiPhan(arr2, 0, n-1, diff) << endl;
    }
}