#include <algorithm>
#include <iostream>
#include <numeric>
#include <vector>

using namespace std;

int main() {
    cin.tie(nullptr);
    cout.tie(nullptr);
    ios_base::sync_with_stdio(false);

    int n;
    cin >> n;
    vector<int> a(n), b(n), d(n);
    for (size_t i = 0; i < n; i++)
    {
        cin >> a[i];
    }
    for (size_t i = 0; i < n; i++)
    {
        cin >> b[i];
        d[i] = a[i] - b[i];
    }

    int m = 0, s = 0, i = 0, j = 0;

    for (j = 0; j < n; j++) {
        s += d[j];
        if (s >= 0) {
            while (i <= j) {
                s -= d[i];
                i++;
            }
        }
        m = min(m, s);
    }

    cout << accumulate(b.begin(), b.end(), 0) + m << endl;
    return 0;
}
/*
4
5 6 7 8
10 1 2 20
*/