#include <iostream>
#include <vector>
#include <map>
#include <bits/stdc++.h>

using namespace std;

#define ll long long
#define cy cout << "YES\n"
#define cn cout << "NO\n"
#define nl "\n"
#define fi first
#define se second
#define MOD 1000000007
#define all(v) v.begin(), v.end()
#define sz(s) s.size()
#define f0r(i, n) for (ll i = 0; i < n; i++)
template <typename T = int>
istream &operator>>(istream &in, vector<T> &v)
{
    for (auto &x : v)
        in >> x;
    return in;
}

template <typename T = int>
ostream &operator<<(ostream &out, const vector<T> &v)
{
    for (const T &x : v)
        out << x << " ";
    return out;
}

void sherry()
{
    ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
#ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout);
#endif
}
ll n;
vector<ll> v1, v2, dp;
ll rec(ll i, ll prev, ll sum)
{
    if (i >= n)
        return -1e9;
    if (i == n - 1)
        return 0;
    ll &ret = dp[i];
    if (~ret)
        return dp[i];
    if (prev == 1)
    {
        ret = max(rec(i + 1, 2, sum + v2[i]), rec(i + 1, -1, sum));
    }
    else if (prev == 2)
    {
        ret = max(rec(i + 1, 1, sum + v1[i]), rec(i + 1, -1, sum));
    }
    else
    {
        ret = max(rec(i + 1, 2, sum + v2[i]), rec(i + 1, 1, sum + v1[i]));
    }
    return ret;
}
void solve()
{
    cin >> n;
    v1 = vector<ll>(n);
    v2 = vector<ll>(n);
    dp.assign(n + 5, -1);
    for (int i = 0; i < n; i++)
    {
        cin >> v1[i];
    }
    for (int i = 0; i < n; i++)
    {
        cin >> v2[i];
    }
    cout << rec(0, -1, 0);
}
int main()
{
    sherry();
    int t = 1;
    // cin >> t;
    while (t--)
        solve();
    return 0;
}