#include <bits/stdc++.h>
using namespace std;
long long int minn(long long int a, long long int b) {
  if (a > b) return b;
  return a;
}
long long int maxx2(long long int a, long long int b) {
  if (a > b) return a;
  return b;
}
long long int maxx(long long int a, long long int b, long long int c) {
  return maxx2(a, maxx2(b, c));
}
long long int gcdd(long long int a, long long int b) {
  if (b == 0)
    return a;
  else
    return gcdd(b, a % b);
}
long long int dsum(long long int n) {
  long long int sum = 0;
  while (n > 0) {
    sum += n % 10;
    n /= 10;
  }
  return sum;
}
long long int poww(long long int a, long long int b) {
  if (b == 0) return 1;
  if (b == 1)
    return a;
  else
    return poww(a, b / 2) * poww(a, b / 2) * poww(a, b % 2);
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long int n;
  cin >> n;
  long long int a[n], c[n], s[n];
  for (long long int i = 0; i < n; i++) {
    cin >> a[i];
  }
  for (long long int i = 0; i < n; i++) {
    cin >> c[i];
  }
  long long int ans = 100000000000000, ans2 = 100000000000000,
                ans3 = 100000000000000;
  for (long long int i = 0; i < n; i++) {
    ans2 = 100000000000000;
    ans3 = 100000000000000;
    for (long long int j = 0; j < i; j++) {
      if (a[j] < a[i]) {
        ans2 = minn(ans2, c[j]);
      }
    }
    for (long long int j = i + 1; j < n; j++) {
      if (a[j] > a[i]) {
        ans3 = minn(ans3, c[j]);
      }
    }
    if (ans2 != 100000000000000 && ans3 != 100000000000000) {
      ans = minn(ans, c[i] + ans2 + ans3);
    }
  }
  if (ans == 100000000000000)
    cout << "-1" << endl;
  else
    cout << ans << endl;
  return 0;
}
