#include <bits/stdc++.h>
#define endl "\n"
typedef long long ll;
typedef unsigned long long ull;
using namespace std;
ll a[100005], b[100005], s[100005], x[100005];
int main(){
ios::sync_with_stdio(false);
int n; cin >> n;
map <int, ll> map;
// map <ll, ll> map1;
for (int i = 1; i <= n; i++) cin >> a[i];
for (int i = 1; i <= n; i++) cin >> b[i];
s[1] = b[1];
for (int i = 1; i <= n; i++){
ll index = 1e10, index1 = 1e10, flag = 1, flag1 = 2;
for (int j = 1; j < i; j++){
if(a[i] > a[j] && map[j] == 1 && (s[j] < index)){
flag = 0;
flag1 = 0;
index = s[j];
}
if(a[i] > a[j] && (index1 == 1e10 || b[j] < b[index1])){
index1 = j;
}
if(a[i] > a[j] && map[j] == 2 && (x[j] < index)){
index = x[j];
flag = 0;
flag1 = 1;
}
}
if(flag == 1){
if(index1 != 1e10){
map[i] = 1;
s[i] = b[i] + s[index1];
}
else{
map[i] = 0;
s[i] = b[i];
}
}
else{
map[i] = 2;
s[i] = index + b[i];
}
}
ll MIN = 5e9;
for (int i = 1; i <= n; i++){
if(map[i] == 2) MIN = min(MIN, s[i]);
}
if(MIN != 5e9) cout << MIN;
else cout << -1;
}
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