#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/priority_queue.hpp>
#define int long long
using namespace std;
const int N=1e4+5;
struct node{
	int id,slf,val;
	bool operator<(const node &T)const{
		return slf==T.slf?val>T.val:slf<T.slf;
	}
};
__gnu_pbds::priority_queue<node> q;
__gnu_pbds::priority_queue<node>::point_iterator its[N];
int a[N],n,b[N];
bool del[N];
signed main(){
	ios::sync_with_stdio(false);
	cin.tie(0),cout.tie(0);
	cin>>n;
	int ans=0;
	for(int i=1;i<=n;i++)cin>>a[i],ans+=a[i];
	for(int i=1;i<=n;i++)cin>>b[i];
	for(int i=1;i<=n;i++)its[i]=q.push((node){i,b[i],b[i-1]+b[i+1]});
	while(not q.empty()){
		int x=q.top().id;
		ans+=q.top().val;q.pop();
		del[x]=true;
		int i=x;
		if(i>1 and del[i-1]==false)q.modify(its[i-1],(node){i-1,b[i-1],(del[i-2]?0:b[i-2])});
		if(i<n and del[i+1]==false)q.modify(its[i+1],(node){i+1,b[i+1],(del[i+2]?0:b[i+2])});
	}
	cout<<ans<<"\n";
}