#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> ii;
const int INF = 2e9;
const ll LINF = 1e18;
const int N = 6e4 + 5;
int n;
ll t[N], r[N];
ll dp[N];
ll memo[N];
ll f(int n) {
if (n == 0) return 0;
if (n == 1) return t[1];
ll& ans = memo[n];
if (ans != -1) return ans;
ans = min(t[n] + f(n - 1), r[n - 1] + f(n - 2));
return ans;
}
int main() {
ios::sync_with_stdio(0); cin.tie(0);
int n;
cin >> n;
for (int i = 1; i <= n; i++) cin >> t[i];
for (int i = 1; i <= n - 1; i++) cin >> r[i];
// // get về
// {
// dp[1] = t[1];
// dp[2] = min(dp[1] + t[2], r[1]);
// for (int i = 3; i <= n; i++) {
// // xét trường hợp người thứ i tự mua và nhờ mua hộ
// dp[i] = min(dp[i - 1] + t[i], dp[i - 2] + r[i - 1]);
// }
// cout << dp[n] << '\n';
// }
// // update lên
// {
// for (int i = 0; i <= n; i++) dp[i] = INF;
// dp[0] = 0;
// for (int i = 0; i < n; i++) {
// // xét trường hợp người thứ i + 1 tự mua hoặc người thứ i + 1 mua hộ i + 2
// dp[i + 1] = min(dp[i + 1], dp[i] + t[i + 1]);
// dp[i + 2] = min(dp[i + 2], dp[i] + r[i + 1]);
// }
// cout << dp[n] << '\n';
// }
// đệ quy
{
memset(memo, -1, sizeof memo);
cout << f(n) << '\n';
}
}
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