/**
 *    author:  otera    
**/
#include<iostream>
#include<string> 
#include<cstdio>
#include<cstring>
#include<vector>
#include<cmath>
#include<algorithm> 
#include<functional>
#include<iomanip>
#include<queue>
#include<deque>
#include<ciso646>
#include<random>
#include<map>
#include<set>
#include<complex>
#include<bitset>
#include<stack>
#include<unordered_map>
#include<unordered_set>
#include<utility>
#include<cassert>
#include<array>
using namespace std;

#define int long long
typedef long long ll;
typedef unsigned long long ul;
typedef unsigned int ui;
typedef long double ld;
const int inf=1e9+7;
const ll INF=1LL<<60 ;
const ll mod=1e9+7 ;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)
typedef complex<ld> Point;
const ld eps = 1e-8;
const ld pi = acos(-1.0);
typedef pair<int, int> P;
typedef pair<ld, ld> LDP;
typedef pair<ll, ll> LP;
#define fr first
#define sc second
#define all(c) c.begin(),c.end()
#define pb push_back
#define debug(x)  cerr << #x << " = " << (x) << endl;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

void solve() {
	int n; cin >> n;
    vector<int> a(n), b(n);
    ll sum = 0;
    rep(i, n) {
        cin >> a[i];
    }
    rep(i, n) {
        cin >> b[i];
        sum += b[i] * 1LL;
    }
    vector<int> odd, even;
    rep(i, n) {
        if(i % 2 == 0) {
            even.push_back(a[i] - b[i]);
        } else {
            odd.push_back(a[i] - b[i]);
        }
    }
    ll ans = sum;
    sort(all(even));
    reverse(all(even));
    sort(all(odd));
    reverse(all(odd));
    rep(i, n / 2) {
        sum += even[i];
        sum += odd[i];
        chmax(ans, sum);
    }
    cout << ans << endl;
}

signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	//cout << fixed << setprecision(10);
	//int t; cin >> t; rep(i, t)solve();
	solve();
    return 0;
}
#include<bits/stdc++.h>
#define ll long long
using namespace std;
char str[200005];
int freq[26];
int main()
{
    scanf("%s", str);
    vector<int>vec, let;

    for(int i=0; str[i]; i++)
    {
        int x= str[i], cnt= 0;
        while(str[i] && str[i]==x)i++, cnt++;i--;
        vec.push_back(cnt);
        let.push_back(x-'a');
    }

    ll res= 0, c= 0;
    while(!vec.empty())
    {
        if(vec.back()>1)
        {
            res+= (c-freq[ let.back() ]);
            memset(freq, 0, sizeof freq);
            c+= vec.back();
            freq[ let.back() ]= c;
        }
        else c++, freq[ let.back() ]++;

        vec.pop_back();
        let.pop_back();
    }

    printf("%lld\n", res);

    return 0;
}
