#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using db = double;
constexpr int mod = 998244353;
constexpr int N = 1e6 + 10;

void solve() {
    int n;
    cin >> n;
    ll suma = 0, sumb = 0;
    vector<ll> a(n), b(n);
    for (int i = 0; i < n; i++) cin >> a[i], suma += a[i];
    for (int i = 0; i < n; i++) cin >> b[i], sumb += b[i];
    if (suma > sumb) b[0] += suma - sumb;
    else a[0] += sumb - suma;
    ll match1 = 0;
    int cnt = 0, maxa1 = 0, maxb1 = 0;
    for (int i = 0; i < n; i++) {
        ll k = min(a[i], b[n - 1 - i]);
        if (k > 0) {
            cnt++;
            match1 += k;
            a[i] -= k;
            b[n - 1 - i] -= k;
            maxa1 = max(maxa1, i);
            maxb1 = max(maxb1, n - 1 - i);
        }
    }
    ll match2 = 0;
    for (int i = 0, j = 0; j < n; j++) {
        if (b[n - 1 - j] == 0) continue;
        while (i <= j) i++;
        while (i < n && a[i] <= b[n - 1 - j]) {
            a[i] = 0;
            b[n - 1 - j] -= a[i];
            match2 += a[i];
            i++;
        }
        if (i < n && a[i] > b[n - 1 - j]) {
            match2 += b[n - 1 - j];
            a[i] -= b[n - 1 - j];
            b[n - 1 - j] = 0;
        }
    }
    if (match2) {
        cout << match1 + match2 << "\n";
        return;
    }
    int maxa2 = 0, maxb2 = 0;
    for (int i = 0; i < n; i++) if (a[i]) maxa2 = i;
    for (int i = 0; i < n; i++) if (b[i]) maxb2 = i;
    if (maxa1 + maxb2 >= n || maxa2 + maxb1 >= n) {
        cout << match1 << "\n";
        return;
    }
    if (cnt >= 2) {
        cout << match1 - 1 << "\n";
        return;
    }
    cout << "0\n";
}
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int tt = 1;
    cin >> tt;
    while (tt--) {
        solve();
    }
    return 0;
}