#include <bits/stdc++.h>
using namespace std;
#define faster ios_base::sync_with_stdio(false) ; cin.tie(NULL)

const long long INF = 1e16;
const int N = 5e5 + 7;
int n;
long long a[N] , b[N] , pre[N] , L[N] , R[N] , _max[N];

void build_L(){
    _max[n + 1] = -INF;
    for (int i = n ; i >= 1 ; --i){
        _max[i] = max(_max[i + 1] , a[i] - pre[i - 1]);
    }
    long long sum = 0;
    for (int i = 1 ; i <= n ; ++i){
        L[i] = sum + _max[i];
        sum += b[i];
    }
}

void build_R(){
    memset(_max , 0 , sizeof _max);
    for (int i = 1 ; i <= n ; ++i){
        _max[i] = max(_max[i - 1] , a[i] - pre[i - 1]);
    }

    long long sum = pre[n];
    for (int i = 1 ; i <= n ; ++i){
        sum -= b[i];
        R[i] = _max[i] - sum;
    }
}

void inp(){
    cin >> n;
    for (int i = 1 ; i <= n ; ++i){
        cin >> a[i];
    }
    for (int i = 1 ; i <= n ; ++i){
        cin >> b[i];
        pre[i] = pre[i - 1] + b[i];
    }
    build_L();
    build_R();
}

void solve(){
    long long res = INF;
    for (int i = 1 ; i <= n ; ++i){
        res = min(res , max(L[i] , R[i - 1]));
    }

    cout << res;
}

int main(){
    faster;
    inp();
    solve();
    return 0;
}