// Source: https://usaco.guide/general/io

#include <bits/stdc++.h>
using namespace std;

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

	long long sum = 0, sum2 = 0, min1 = LLONG_MAX, max2 = LLONG_MIN, min1i = 0, max2i = 0, max2min1i = 0;
	for (long long i = 0; i < n; i++) {
		cin >> b[i];
		sum2 += b[i];
		sum += b[i] - a[i];
		if (sum < min1) {
			min1 = sum;
			min1i = i;
		}
		if (sum - min1 > max2) {
			max2 = sum - min1;
			max2i = i;
			max2min1i = min1i;
		}
	}

	cout << sum2 - max2;
}