#include<bits/stdc++.h>
#define int long long
#define endl '\n'
#define PB push_back
#define pii pair<int, int>
using namespace std;
const int N = 2e5 + 5;
const int INF = 1e18;
int a[N], b[N], dp[N][2];
void solve(){
    int n;
    cin >> n;
    for(int i=1; i<=n; i++) cin >> a[i];
    for(int i=1; i<=n; i++) cin >> b[i];

    memset(dp, 0x3f, sizeof(dp));
    dp[1][1] = b[1];
    for(int i=2; i<n; i++){
        dp[i][0] = dp[i-1][1];
        dp[i][1] = min(dp[i-1][0], dp[i-1][1]) + b[i];
    }
    dp[n][1] = min(dp[n-1][0], dp[n-1][1]) + b[n];

    int ans = 0;
    for(int i=1; i<=n; i++){
        ans = max(min(dp[i][0], dp[i][1]), ans) + a[i];
    }
    cout << ans << endl;
}
signed main(){
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    int T = 1;
    // cin >> T;
    while(T--){
        solve();
    }
}