#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 = 1e6 + 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];
PII p[N];
int m;
bool check(int k, int t)
{
    return p[k].second + t >= m;
}
int esum[N];
void solve()
{
    scanf("%lld", &m);
    int suma = 0, sumb = 0;
    for (int i = 0; i < m; i++) scanf("%lld", &a[i]), suma += a[i];
    for (int i = 0; i < m; i++) scanf("%lld", &b[i]), sumb += b[i];
    if (sumb > suma) swap(a, b);
    int n = 0;
    for (int i = 0; i < m; i++) {
        if (b[i]) p[++n] = {b[i], i};
    }
    int ans = 0;
    int ca = -1, cb = -1, ssum = inf;
    for (int i = 1; i < m; i++) {
        if (!a[i]) continue;
        int l = 1, r = n, tmp = r;
        while (l < r) {
            int mid = (l + r) / 2;
            if (check(mid, i)) {
                r = mid ;
                tmp = mid;
            }
            else {
                l = mid + 1;
            }
        }
        tmp=l;
        if (ssum > i + p[tmp].second) {
            ca = i;
            cb = p[tmp].second;
            ssum = i + p[tmp].second;
        }
    }

    if (ca != -1 && cb != -1) {
//        cout << ca << " " << cb << " " << endl;
        a[ca]--;
        b[cb]--;
        ans++;
    }
    else {
        printf("0\n");
        return;
    }
//    for (int i = 0; i < m; i++) cout << a[i] << endl;
    int cnt = 0;
    for (int i = m - 1; i >= 0; i--) {
        esum[i] = b[i] + esum[i + 1];
    }
//    for (int i = 0; i < m; i++) cout << esum[i] << " ";
    for (int i = 0; i < m; i++) {
        if (a[i] >= esum[max(m - i - 1, 0LL)] - cnt) {
            ans += esum[max(m - i - 1, 0LL)] - cnt;
            a[i] -= esum[max(m - i - 1, 0LL)] - cnt;
            cnt = esum[max(m - i - 1, 0LL)];
        }
        else {
            ans += a[i];
            cnt += a[i];
            a[i] = 0;
        }
    }
    ans += a[m - 1];
//    cout << "olahfc\n";
    printf("%lld\n", ans);
}

signed main()
{
//    ios::sync_with_stdio(false), cin.tie(0);
    int _;
    scanf("%lld", &_);
//    _ = 1;
	int id=0;
    while (_--) {
        solve();
        id++;
    }
    return 0;
}