#include <bits/stdc++.h>
using namespace std;
using i64 = long long;
using pii = pair<i64, i64>;
void solve()
{
    int n;
    cin >> n;
    map<i64, i64> s, ss, t;
    for (int i=0;i<n;++i)
    {
        int x;
        cin >> x;
        if (x) s[i] = x;
    }
    for (int i=0;i<n;++i)
    {
        int x;
        cin >> x;
        if (x) t[i] = x;
    }
    s[0] = 0x3f3f3f3f3f3f3f3f; t[0] = 0x3f3f3f3f3f3f3f3f;
    map<pii, i64> mp;
    while (s.size() && t.size())
    {
        while (s.size() && s.begin()->first + t.rbegin()->first < n - 1)
        {
            ss.insert(*s.begin());
            s.erase(s.begin());
        }
        if (!s.size()) break;
        i64 k = min(s.begin()->second, t.rbegin()->second);
        mp[pii(s.begin()->first, t.rbegin()->first)] += k;
        if (s.begin()->second == k) s.erase(s.begin()); else s.begin()->second -= k;
        if ((--t.end())->second == k) t.erase(--t.end()); else (--t.end())->second -= k;
    }
    i64 ms = 0, mt = 0;
    for (auto [x, y] : s) ms = max(ms, x);
    for (auto [x, y] : ss) ms = max(ms, x);
    for (auto [x, y] : t) mt = max(mt, x);
    int ok = 0;
    i64 sum = 0;
    for (auto [p, x] : mp) sum += x;
    for (auto [p, x] : mp)
        if (max(p.first, ms) + max(p.second, mt) >= n)
        {
            ok = 1;
            break;
        }
    if (ok) return cout << sum << '\n', void();
    ms = mt = 0;
    for (auto [p, x] : mp) ms = max(ms, p.first), mt = max(mt, p.second);
    if (ms + mt < n) return cout << "0\n", void();
    cout << sum - 1 << '\n';
}
int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    int t;
    cin >> t;
    while (t--) solve();
    return 0;
}