#include <bits/stdc++.h>

using namespace std;
#define all(x) (x).begin(), (x).end()
using ll = long long;

template<typename T>
ostream &operator<<(ostream &os, const vector<T> &v) {
    for (int i = 0; i < int(v.size()); i++) os << v[i] << (i + 1 == int(v.size()) ? "" : " ");
    return os;
}

#ifdef LOCAL
#define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" << endl;
#else
#define debug(x) void(0)
#endif

constexpr int INF = (1 << 30) - 1;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n;
    cin >> n;
    vector<int> a(n), b(n);
    for (int &x: a) cin >> x;
    for (int &x: b) cin >> x;

    vector<int> ord(n);
    iota(all(ord), 0);
    sort(all(ord), [&](int l, int r) { return a[l] < a[r]; });
    vector<int> na(n), nb(n);
    for (int i = 0; i < n; i++) {
        na[i] = a[ord[i]];
        nb[i] = b[ord[i]];
    }
    if (not is_sorted(all(b))) {
        cout << -1 << "\n";
        return 0;
    }

    vector<int> init(n - 1), to(n - 1);
    for (int i = 0; i + 1 < n; i++) {
        init[i] = a[i + 1] - a[i];
        to[i] = b[i + 1] - b[i];
        if (init[i] < to[i]) {
            cout << -1 << "\n";
            return 0;
        }
    }

    int ans = INF;
    map<pair<vector<int>, int>, int> mp;
    queue<pair<vector<int>, int>> que;
    que.emplace(init, a[0]);
    mp[{init, a[0]}] = 0;
    while (not que.empty()) {
        auto [v, f] = que.front();
        que.pop();
        int cur = mp[{v,f}];
        bool ok = true, same = true;
        for (int i = 0; i < n - 1; i++) {
            if (v[i] < to[i])ok = false;
            if (v[i] != to[i]) same = false;
        }
//        debug(v);
//        debug(f);
//        debug(cur);
        if (not ok) continue;
        if (same and f <= b[0]) {
            ans = min(ans, cur + (b[0] - f));
            continue;
        }
        for (int k = 0; k < 2; k++) {
            vector<int> u(n - 1);
            int x = f + k;
            for (int i = 0; i < n - 1; x += v[i++]) {
                u[i] = v[i] / 2;
                if ((v[i] & 1) and (x & 1)) u[i]++;
            }
            int nf = (f + k) / 2, ncur = cur + k + 1;
            if (not mp.count({u,nf})) que.emplace(u,nf);
            if (not mp.count({u,nf}) or ncur< mp[{u,nf}])
                mp[{u,nf}] = ncur;
        }
    }

    cout << (ans == INF ? -1 : ans) << "\n";
    return 0;
}