#include <iostream>
#include <vector>
#include <climits>
using namespace std;
int main() {
int n;
cin >> n;
vector<int> a(n), b(n);//str req, gain
for (int i = 0; i < n; i++) cin >> a[i];
for (int i = 0; i < n; i++) cin >> b[i];
vector<int> gain(n), gain_rev(n), str(n), str_rev(n), dp(n);
//gain = str gained from going i to end, gain_rev = str gained from first i
//str = str req to go from i to end, str_rev = str req to go from 1 to i, dp[i] = str_rev[i] - gain[i]
gain[n-1] = b[n-1];
for (int i = n-2; i >= 0; i--) gain[i] = gain[i+1] + b[i];
gain_rev[0] = b[0];
for (int i = 1; i < n; i++) gain_rev[i] = gain_rev[i-1] + b[i];
str[n-1] = a[n-1];
for (int i = n-2; i >= 0; i--) str[i] = max(0,max(a[i], str[i+1] - b[i]));
str_rev[0] = a[0];
for (int i = 1; i < n; i++) str_rev[i] = max(0,max(str_rev[i-1], a[i] - gain_rev[i-1]));
for (int i = 0; i < n; i++) dp[i] = max(0,str_rev[i] - gain[i]);
int m = INT_MAX;
for (int i = 0; i < n; i++) {
m = min(m, max(str[i], dp[i]));
}
cout << m << endl;
}
