#include <bits/stdc++.h>
using namespace std;
typedef long long LL;
typedef long double LD;
#define int LL
#define double LD
#define endl "\n"
typedef pair<int, int> PII;
const int N = 5e5 + 5;
const int INF = 0x3f3f3f3f;
const int inf = 0x3f3f3f3f3f3f3f3f;
const double PI = acosl(-1.0);
const double eps = 1e-8;
const int MOD = 1e9 + 7;

int a[N], b[N];
int m;
bool check(int k, int t)
{
    return k + t >= m;
}
void solve()
{
    cin >> m;
    int suma = 0, sumb = 0;
    for (int i = 0; i < m; i++) cin >> a[i], suma += a[i];
    for (int i = 0; i < m; i++) cin >> b[i], sumb += b[i];
     if (sumb > suma) {
        int mid;
        for (int i = 0; i < m; i++) {
            mid = a[i];
            a[i] = b[i];
            b[i] = mid;
        }
        mid = suma;
        suma = sumb;
        sumb = mid;
    }
    int ans = 0;
    int ca = -1, cb = -1, ssum = inf;
    for (int i = 1; i < m; i++) {
        int l = 0, r = m - 1, tmp = r;
        while (l <= r) {
            int mid = (l + r) / 2;
            if (check(mid, i)) {
                r = mid - 1;
                tmp = mid;
            }
            else {
                l = mid + 1;
            }
        }
        if (ssum > i + tmp) {
            ca = i;
            cb = tmp;
            ssum = i + tmp;
        }
    }
    if (ca != -1 && cb != -1) {
//        cout << ca << " " << cb << " " << endl;
        a[ca]--;
        b[cb]--;
        ans++;
    }
    else {
        cout << 0 << endl;
        return;
    }
    int r = m - 1;
    for (int i = 0; i < m; i++) {
        while (a[i] >= b[r] && (i + r) >= m - 1 && r >= 0) {
            ans += b[r];
            a[i] -= b[r];
            r--;
        }
        if (r < 0) {
            ans += a[m - 1];
            cout << ans << endl;
            return;
        }
    }
//    cout << "olahfc\n";
    cout << ans << endl;
}

signed main()
{
    ios::sync_with_stdio(false), cin.tie(0);
    int _;
    cin >> _;
//    _ = 1;
    while (_--) {
        solve();
    }
    return 0;
}