#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int main(){

    int N;
    cin >> N;

    vector<long long> A(N), B(N);
    for (int i = 0; i < N; i++){
        cin >> A[i];
    }
    long long baseCost = 0;
    for (int i = 0; i < N; i++){
        cin >> B[i];
        baseCost += B[i];
    }

    // d[i] = a[i] - b[i]
    long long currentMin = 0, bestMin = 0;
    for (int i = 0; i < N; i++){
        long long d = A[i] - B[i];
        currentMin = min(0LL, currentMin + d);
        bestMin = min(bestMin, currentMin);
    }

    long long result = baseCost + bestMin;
    cout << result << "\n";

    return 0;
}