#include<bits/stdc++.h>
using namespace std;
#define endl "\n"
#define int long long
#define faster() ios::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
#define MOD 1000000007
 
void solve(){
    int n  ; cin >> n ;
    int t[n + 1] , r[n + 1];
    for(int i = 1 ; i <= n ; i++) cin >> t[i];
    for(int i = 1 ; i <= n - 1 ; i++) cin >> r[i];
 
    int dp[n + 1] = {}; // dp[i] : thoi gian toi thieu de phuc vu tu nguoi thu 1 => nguoi thu i
    dp[1] = t[1] ; // nguoi dau tien tu mua ve 
    for(int i = 2 ; i <= n ; i++){
        dp[i] = min(dp[i - 1] + t[i] , dp[i - 2] + r[i - 1]);
    }
    cout << dp[n] << endl;
}
 
signed main(){
    faster();
    int test = 1;
    // cin >> test ;
    while(test--){
        solve();
    }
}

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