#include <iostream>
#include <iomanip>
#include <string>
#include <cmath>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
#include <unordered_map>
#include <unordered_set>
#include <list>
#include <stack>
#include <queue>
#include <bitset>
#include <numeric>
#include <cassert>
#ifdef DEBUG
#include "./Lib/debug.hpp"
#else
#define dump(...)
template<class T>inline auto d_val(T a, T b) { return a; }
#endif

/* (=＾o＾=) */
#define int ll

/* macro */
#define FOR(i, b, e) for(ll i = (ll)(b); i < (ll)(e); ++i)
#define RFOR(i, b, e) for(ll i = (ll)(e-1); i >= (ll)(b); --i)
#define REP(i, n) FOR(i, 0, n)
#define RREP(i, n) RFOR(i, 0, n)
#define REPC(x,c) for(const auto& x:(c))
#define REPI2(it,b,e) for(auto it = (b); it != (e); ++it)
#define REPI(it,c) REPI2(it, (c).begin(), (c).end())
#define RREPI(it,c) REPI2(it, (c).rbegin(), (c).rend())
#define REPI_ERACE2(it, b, e) for(auto it = (b); it != (e);)
#define REPI_ERACE(it, c) REPI_ERACE2(it, (c).begin(), (c).end())
#define ALL(x) (x).begin(),(x).end()
#define cauto const auto&
/* macro func */
#define SORT(x) do{sort(ALL(x));}while(false)
#define RSORT(x) do{sort((x).rbegin(),(x).rend());}while(false)
#define UNIQUE(v) do{v.erase( unique(v.begin(), v.end()), v.end() );}while(false)
#define MAX(x,y) do{x = std::max(x,y);}while(false)
#define MIN(x,y) do{x = std::min(x,y);}while(false)
#define BR do{cout<<"\n";}while(false)

/* type define */
using ll = long long;
using PAIR = std::pair<ll, ll>;
using VS = std::vector<std::string>;
using VL = std::vector<long long>;
using VVL = std::vector<VL>;
using VVVL = std::vector<VVL>;
using VD = std::vector<double>;
template<class T>
using V = std::vector<T>;

/* using std */
using std::cout;
constexpr char endl = '\n';
using std::cin;
using std::sort;
using std::pair;
using std::string;
using std::stack;
using std::queue;
using std::vector;
using std::list;
using std::map;
using std::unordered_map;
using std::multimap;
using std::unordered_multimap;
using std::set;
using std::unordered_set;
using std::unordered_multiset;
using std::multiset;
using std::bitset;
using std::priority_queue;

/* constant value */
constexpr ll MOD = 1000000007;
//constexpr ll MOD = 998244353;

/* Initial processing  */
struct Preprocessing { Preprocessing() { std::cin.tie(0); std::ios::sync_with_stdio(0); }; }_Preprocessing;

/* Remove the source of the bug */
signed pow(signed, signed) { assert(false); return -1; }

/* define hash */
namespace std { template <>	class hash<std::pair<ll, ll>> { public:	size_t operator()(const std::pair<ll, ll>& x) const { return hash<ll>()(1000000000 * x.first + x.second); } }; }

/* input */
template<class T> std::istream& operator >> (std::istream& is, vector<T>& vec) { for (T& x : vec) is >> x; return is; }

//=============================================================================================

ll n;
ll at(ll i) {
	return (i + n) % n;
}

ll dov(VL& b, ll i, VL& a) {
	ll cnt = 0;
	ll j = (i + n - 1);
	ll val = b[at(j - 1)] + b[at(j + 1)];
	if (val < b[at(j)]) {
		if (val == 0) { return 0; }
		cnt += b[at(j)] / val;
		b[at(j)] %= val;
		if (b[at(j)] < a[at(j)]) {
			ll t = (a[at(j)] - b[at(j)] + 1) / val;
			cnt -= t;
			b[at(j)] += t * val;
		}
		cnt += dov(b, j, a);
	}

	j = (i + 1);
	val = b[at(j - 1)] + b[at(j + 1)];
	if (val < b[at(j)]) {
		if (val == 0) { return 0; }
		cnt += b[at(j)] / val;
		b[at(j)] %= val;
		if (b[at(j)] < a[at(j)]) {
			ll t = (a[at(j)] - b[at(j)] + 1) / val;
			cnt -= t;
			b[at(j)] += t * val;
		}
		cnt += dov(b, j, a);
	}
	return cnt;
}

signed main() {
	cin >> n;
	VL a(n), b(n);
	cin >> a >> b;

	REP(i, n) {
		if (a[i] > b[i]) {
			cout << -1 << endl;
			return 0;
		}
	}

	ll cnt = 0;
	REP(i, n) {
		ll val = b[at(i - 1)] + b[at(i + 1)];
		if (val < b[at(i)]) {
			if (val == 0) { break; }
			cnt += b[at(i)] / val;
			b[at(i)] %= val;
			if (b[at(i)] < a[at(i)]) {
				ll t = (a[at(i)] - b[at(i)] + 1) / val;
				cnt -= t;
				b[at(i)] += t * val;
			}
			cnt += dov(b, i, a);
		}
	}
	dump(b);
	if (a == b) {
		cout << cnt << endl;
	} else {
		cout << -1 << endl;
	}
}

Measured memory_bytes: 3328