#include <bits/stdc++.h>
 
using namespace std;  
 
typedef long long ll;  
typedef pair<int, int> ii;  
 
const int INF = 1e9;   
const ll LINF = 1e18; 
 
const int N = 6e4 + 5;  
 
int n;  
int t[N];
int r[N]; 
ll dp[N]; // dp[i] = Tổng thời gian phục vụ bán vé nhỏ nhất khi xét đến người thứ i  
 
int main() {
	ios::sync_with_stdio(0); cin.tie(0);  	
	cin >> n;   
	for (int i = 1; i <= n; i++) cin >> t[i];  
	for (int i = 1; i <= n - 1; i++) cin >> r[i]; 
 
	dp[0] = 0;  
	dp[1] = t[1]; 
	for (int i = 2; i <= n; i++) {
		// Để tính dp[i] thì ta xét 2 trường hợp là người thứ i tự mua vé 
		// hoặc nhờ người thứ i - 1 mua hộ vé cho cả hai
		dp[i] = min(dp[i - 1] + t[i], dp[i - 2] + r[i - 1]); 
	}
 
	cout << dp[n] << '\n'; 
}

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