#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main() {
// Optimize standard I/O operations for competitive programming
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int n;
if (!(cin >> n)) return 0;
// Use long long to prevent overflow, as constraints can push sums to ~5 * 10^14
vector<long long> a(n), b(n);
for (int i = 0; i < n; i++) cin >> a[i];
for (int i = 0; i < n; i++) cin >> b[i];
// 1. Calculate Prefix Sums of Strength Gains
// P[i] stores the total strength gained AFTER defeating monsters 0 to i
vector<long long> P(n);
P[0] = b[0];
for (int i = 1; i < n; i++) {
P[i] = P[i-1] + b[i];
}
// Helper lambda to get strength gained BEFORE fighting monster i
auto get_G = [&](int i) {
return (i == 0) ? 0LL : P[i-1];
};
// 2. Calculate Baseline Deficits (Assuming we start at index 0)
// D[i] = Required strength for monster i minus the strength we naturally built up to reach it
vector<long long> D(n);
for (int i = 0; i < n; i++) {
D[i] = a[i] - get_G(i);
}
// 3. Precompute Prefix and Suffix Maximums of the Deficits
vector<long long> pref_max(n), suff_max(n);
pref_max[0] = D[0];
for (int i = 1; i < n; i++) {
pref_max[i] = max(pref_max[i-1], D[i]);
}
suff_max[n-1] = D[n-1];
for (int i = n - 2; i >= 0; i--) {
suff_max[i] = max(suff_max[i+1], D[i]);
}
// Total strength gained from defeating ALL monsters
long long P_total = P[n-1];
// Initialize minimum required initial strength to infinity
long long min_initial_strength = 2e18;
// 4. Evaluate Every Starting Position in O(1) Time per position
for (int j = 0; j < n; j++) {
long long G_j = get_G(j);
// Phase 1: Fighting monsters from j to the end of the line (n-1)
long long req_phase1 = suff_max[j] + G_j;
// Phase 2: Wrapping around and fighting monsters from 0 to j-1
long long req_phase2 = -2e18; // Default to very small if j == 0 (no Phase 2)
if (j > 0) {
req_phase2 = pref_max[j-1] + G_j - P_total;
}
// The minimum strength needed if starting at j is the max requirement of both phases (or 0)
long long current_req = max({0LL, req_phase1, req_phase2});
// Update global minimum
min_initial_strength = min(min_initial_strength, current_req);
}
cout << min_initial_strength << "\n";
return 0;
}
