#include <bits/stdc++.h>
using namespace std;

typedef long long int ll;

int main() {
	ll n;
	cin >> n;
	
	vector<int> a(n, 0);
	vector<int> b(n, 0);
	
	// Reading array a
	for(int i=0; i<n; i++) {
		cin >> a[i];
	}
	
	// Reading array b
	for(int i=0; i<n; i++) {
		cin >> b[i];
	}
	
	vector<int> dp(n, 0);
	
	dp[0] = max(a[0], b[0]);
	dp[1] = max(dp[0], max(a[1], b[1]));
	
	for(int i=2; i<n; i++) {
		int x = dp[i-1];
		int y = b[i] + dp[i-2];
		int z = a[i] + dp[i-2];
		
		dp[i] = max(x, max(y,z));
		cout << i << " : " << dp[i] << endl;
	}
	
	cout << dp[n-1];
	return 0;
}