#include <bits/stdc++.h>
using namespace std;
const int inf = 1e7;
void solve()
{
    int m;
    cin >> m;
    vector<int> a(m), b(m);
    int sum1 = 0, sum2 = 0;
    for (auto &x : a)
        cin >> x, sum1 += x;
    for (auto &x : b)
        cin >> x, sum2 += x;
    bool check = 0;
    if (sum1 < sum2)
        a[0] += sum2 - sum1;
    if (sum1 > sum2)
        b[0] += sum1 - sum2;
    bool tag = 0;
    int tmp = 0;
    int ans = 0;
    for (int i = 0; i < m; i++)
    {
        if (tmp)
            tag = 1;
        tmp += b[m - 1 - i];
        int delta = min(a[i], tmp);
        tmp -= delta;
        ans += delta;
    }
    cout << max(0, ans - (tag ^ 1)) << endl;
}
signed main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int t;
    cin >> t;
    while (t--)
        solve();
}