#include <bits/stdc++.h>
#include <random>

using namespace std;

typedef unsigned long long ull;
typedef long long ll;
typedef long double ld;
#define double ld
#define int ll
//#define int __int128
//#define ll __int128
typedef pair<int, int   > pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<pii> vpi;
typedef vector< vi > vvi;
typedef vector< vvi > vvvi;
typedef vector<short> vs;
typedef vector<vs> vvs;
typedef vector<vvs> vvvs;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<vvl> vvvl;
typedef vector<ld> vld;
typedef vector<vld> vvld;
typedef vector<vvld> vvvld;
typedef vector<string> vst;
typedef vector<vst> vvst;
typedef pair<ld, ld> pld;
//typedef complex<double> base;

#define inmin(a, b) a = min(a, (b))
#define inmax(a, b) a = max(a, (b))
#define ALL(a) a.begin(),a.end()
#define RALL(a) a.rbegin(),a.rend()
#define sqr(x) ((x) * (x))
#define fori(i, n) for(int i = 0; i < (int)(n); ++i)
#define SZ(a) ((int)((a).size()))
#define triple(T) tuple<T, T, T>
#define quad(T) tuple<T, T, T, T>
#define watch(x) cerr << (#x) << " = " << (x) << endl;

#ifdef RUS_HOME
#define cerr cout
#else
#define cerr if (false) cerr
#endif

const double PI = 2 * acos(0.0);
#define rand shittttty_shit
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
mt19937_64 rng_64(chrono::steady_clock::now().time_since_epoch().count());

const string DIGITS = "0123456789";
const string ALPH = "abcdefghijklmnopqrstuvwxyz";

template <class T0, class T1>
inline ostream & operator << (ostream &out, pair<T0, T1> &a) {
    return out << "{" << a.first << ", " << a.second << "}";
}

template <class T0, class T1, class T2>
inline ostream & operator << (ostream &out, tuple<T0, T1, T2> &a) {
    return out << "{" << get<0>(a) << ", " << get<1>(a) << ", " << get<2>(a) << "}";
}

template <class T0, class T1, class T2, class T3>
inline ostream & operator << (ostream &out, tuple<T0, T1, T2, T3> &a) {
    return out << "{" << get<0>(a) << ", " << get<1>(a) << ", " << get<2>(a) << ", " <<  get<3>(a) << "}";
}

template<class T>
inline ostream & operator << (ostream &out, vector<T> &a) {
    out << "[";
    fori (i, a.size())
        out << a[i] << vector<string>{", ", "]  "}[i + 1 == a.size()];
    return out;
}



void smain();

signed main() {
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

#ifdef RUS_HOME
    freopen("input.txt", "r", stdin);
    clock_t start = clock();
#endif
    cout << setprecision(12) << fixed;
    smain();
#ifdef RUS_HOME
    cout << "\n\n\n\nTOTAL EXECUTION TIME: " << float( clock () - start ) /  CLOCKS_PER_SEC << endl;
#endif
    return 0;
}

const int N = 3e5 + 100, LOG = 20, oo = 1e9;

int n, a[N], b[N];
bool used[N];

bool kek(int nm) {
    int ls = nm - 1, nx = nm + 1;
    if (ls == -1)
        ls = n - 1;
    if (nx == n)
        nx = 0;
    if (b[nm] > a[nm] && b[nm] > b[ls] + b[nx])
        return true;
    return false;
}

void smain() {


    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> a[i];
    }
    for (int i = 0; i < n; i++) {
        cin >> b[i];
    }
    set <pii> st;
    for (int i = 0; i < n; i++) {
        if (kek(i))
            st.insert({b[i], i});
    }
    int ans = 0;
    while (st.size()) {
        auto it = st.end(); it--;
        pii p = *it;
        int nm = p.second;
        int ls = nm - 1, nx = nm + 1;
        if (ls == -1)
            ls = n - 1;
        if (nx == n)
            nx = 0;

        st.erase(it);
        ans += (b[nm] - a[nm]) / (b[ls] + b[nx]);
        if ((b[nm] - a[nm]) / (b[ls] + b[nx]) == 0) {
            cout << -1;
            return;
        }
        b[nm] = a[nm] + (b[nm] - a[nm]) % (b[ls] + b[nx]);

        if (kek(nm)) {
            st.insert({b[nm], nm});
        }
        if (kek(ls)) {
            st.insert({b[ls], ls});
        }
        if (kek(nx)) {
            st.insert({b[nx], nx});
        }

    }


    for (int i = 0; i < n; i++) {
        if (b[i] != a[i]) {
            cout << -1;
            return;
        }
    }

    cout << ans;


}


Measured memory_bytes: 10240