#include<bits/stdc++.h>
#define M 60004
using namespace std;
 
int n;
int t[M], r[M];
long long dp[M];
 
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);     cout.tie(0);
    #define name "baitap"
 
    cin >> n;
    for(int i = 1; i <= n; i++)
        cin >> t[i];
    for(int i = 1; i < n; i++)
        cin >> r[i];
    dp[1] = t[1];
    dp[2] = min(t[1] + t[2], r[1]);
    for(int i = 3; i <= n; i++)
        dp[i] = min(dp[i - 1] + t[i], dp[i - 2] + r[i - 1]);
    cout << dp[n];
}
 

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