#include <algorithm>
#include <bitset>
#include <cassert>
#include <cctype>
#include <chrono>
#define _USE_MATH_DEFINES
#include <cmath>
#include <cstdio>
#include <cstring>
#include <ctime>
#include <deque>
#include <functional>
#include <iostream>
#include <iterator>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <string>
#include <tuple>
#include <utility>
#include <vector>
using namespace std;

#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()

const int INF = 0x3f3f3f3f;
const long long LINF = 0x3f3f3f3f3f3f3f3fLL;
const double EPS = 1e-8;
const int MOD = 1000000007; // 998244353;
const int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1};
/*-------------------------------------------------*/
template <typename Monoid>
struct RMQ {
  RMQ(int sz, const Monoid &UNITY) : UNITY(UNITY) {
    init(sz);
    dat.assign((n << 1) - 1, UNITY);
  }

  RMQ(const vector<Monoid> &a, const Monoid &UNITY) : UNITY(UNITY) {
    int a_sz = a.size();
    init(a_sz);
    dat.resize((n << 1) - 1);
    REP(i, a_sz) dat[n - 1 + i] = a[i];
    for (int i = n - 2; i >= 0; --i) dat[i] = max(dat[(i << 1) + 1], dat[(i << 1) + 2]);
  }

  void update(int node, Monoid value) {
    node += n - 1;
    dat[node] = value;
    while (node > 0) {
      node = (node - 1) >> 1;
      dat[node] = max(dat[(node << 1) + 1], dat[(node << 1) + 2]);
    }
  }

  Monoid query(int a, int b) { return query(a, b, 0, 0, n); }

  int find(int a, int b, Monoid value) { return find(a, b, value, 0, 0, n); }

  Monoid operator[](const int idx) const { return dat[idx + n - 1]; }

private:
  int n = 1;
  const Monoid UNITY;
  vector<Monoid> dat;

  void init(int sz) { while (n < sz) n <<= 1; }

  Monoid query(int a, int b, int node, int left, int right) {
    if (right <= a || b <= left) return UNITY;
    if (a <= left && right <= b) return dat[node];
    return max(query(a, b, (node << 1) + 1, left, (left + right) >> 1), query(a, b, (node << 1) + 2, (left + right) >> 1, right));
  }

  int find(int a, int b, Monoid value, int node, int left, int right) {
    if (dat[node] < value || right <= a || b <= left) return -1;
    if (right - left == 1) return node - (n - 1);
    int res_l = find(a, b, value, (node << 1) + 1, left, (left + right) >> 1);
    if (res_l != -1) return res_l;
    return find(a, b, value, (node << 1) + 2, (left + right) >> 1, right);
  }
};

int main() {
  cin.tie(0); ios::sync_with_stdio(false);
  // freopen("input.txt", "r", stdin);

  int n; cin >> n;
  vector<long long> a(n), b(n); REP(i, n) cin >> a[i]; REP(i, n) cin >> b[i];
  vector<long long> init(n);
  REP(i, n) {
    init[i] = b[i] - a[i];
    if (init[i] < 0) {
      cout << -1 << '\n';
      return 0;
    }
  }
  RMQ<long long> rmq(init, -LINF);
  long long ans = 0;
  while (true) {
    int idx = rmq.find(0, n, rmq.query(0, n));
    long long tmp = rmq[idx];
    if (rmq[idx] == 0) break;
    long long sum = rmq[(idx - 1 + n) % n] + a[(idx - 1 + n) % n] + rmq[(idx + 1) % n] + a[(idx + 1) % n];
    if (sum > rmq[idx]) {
      cout << -1 << '\n';
      return 0;
    }
    ans += rmq[idx] / sum;
    rmq.update(idx, rmq[idx] - rmq[idx] / sum * sum);
  }
  cout << ans << '\n';
  return 0;
}


Measured memory_bytes: 9092