#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define pb push_back
#define mp make_pair
#define all(a) begin(a),end(a)
#define FOR(x,val,to) for(int x=(val);x<int((to));++x)
#define FORE(x,val,to) for(auto x=(val);x<=(to);++x)
#define FORR(x,arr) for(auto &x: arr)
#define FORS(x,plus,arr) for(auto x = begin(arr)+(plus); x != end(arr); ++x)
#define FORREV(x,plus,arr) for(auto x = (arr).rbegin()+(plus); x !=(arr).rend(); ++x)
#define REE(s_) {cout<<s_<<'\n';exit(0);}
#define GET(arr) for(auto &i: (arr)) sc(i)
#define whatis(x) cerr << #x << " is " << (x) << endl;
#define e1 first
#define e2 second
#define INF 0x7f7f7f7f
typedef std::pair<int,int> pi;
typedef std::vector<int> vi;
typedef std::vector<std::string> vs;
typedef int64_t ll;
typedef uint64_t ull;
#define umap unordered_map
#define uset unordered_set
using namespace std;
using namespace __gnu_pbds;

#ifdef _WIN32
#define getchar_unlocked() _getchar_nolock()
#define _CRT_DISABLE_PERFCRIT_LOCKS
#endif
template<class L, class R> ostream& operator<<(ostream &os, map<L, R> P) { for(auto const &vv: P)os<<"("<<vv.first<<","<<vv.second<<")"; return os; }
template<class T> ostream& operator<<(ostream &os, set<T> V) { os<<"[";for(auto const &vv:V)os<<vv<<","; os<<"]"; return os; }
template<class T> ostream& operator<<(ostream &os, vector<T> V) { os<<"[";for(auto const &vv:V)os<<vv<<","; os<<"]"; return os; }
template<class L, class R> ostream& operator<<(ostream &os, pair<L, R> P) { os<<"("<<P.first<<","<<P.second<<")"; return os; }
inline int fstoi(const string &str){auto it=str.begin();bool neg=0;int num=0;if(*it=='-')neg=1;else num=*it-'0';++it;while(it<str.end()) num=num*10+(*it++-'0');if(neg)num*=-1;return num;}
inline void getch(char &x){while(x = getchar_unlocked(), x < 33){;}}
inline void getstr(string &str){str.clear(); char cur;while(cur=getchar_unlocked(),cur<33){;}while(cur>32){str+=cur;cur=getchar_unlocked();}}
template<typename T> inline bool sc(T &num){ bool neg=0; int c; num=0; while(c=getchar_unlocked(),c<33){if(c == EOF) return false;} if(c=='-'){ neg=1; c=getchar_unlocked(); } for(;c>47;c=getchar_unlocked()) num=num*10+c-48; if(neg) num*=-1; return true;}template<typename T, typename ...Args> inline void sc(T &num, Args &...args){ bool neg=0; int c; num=0; while(c=getchar_unlocked(),c<33){;} if(c=='-'){ neg=1; c=getchar_unlocked(); } for(;c>47;c=getchar_unlocked()) num=num*10+c-48; if(neg) num*=-1; sc(args...); }
template<typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>; //s.find_by_order(), s.order_of_key() <- works like lower_bound
template<typename T> using ordered_map = tree<T, int, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#define N 1000001

/* set<vi> st; */

/* void rec(vi c){ */
/*     FOR(i,0,c.size()){ */
/*         int nw = c[(i+1)%c.size()]+c[i]+c[(i+c.size()-1)%c.size()]; */
/*         if(nw > 10) continue; */
/*         int was = c[i]; */
/*         c[i] = nw; */
/*         vi cs = c; */
/*         sort(all(cs)); */
/*         if(st.insert(cs).e2){ */
/*             rec(c); */
/*         } */
/*         c[i] = was; */
/*     } */
/* } */

int main(){
    ios_base::sync_with_stdio(0);cin.tie(0);
    ll n;
    sc(n);
    ll a[n];
    GET(a);
    ll b[n];
    GET(b);
    priority_queue<pair<ll,ll>> pq;
    FOR(i,0,n){
        if(b[i] < a[i]) REE(-1)
        if(b[i] > a[i]) pq.push({b[i],i});
    }
    ll res = 0;
    while(!pq.empty()){
        /* FOR(i,0,n){ */
        /*     cerr << b[i] << ' '; */
        /* } */
        /* cerr << '\n'; */
        /* cerr << '\n'; */
        ll cr = pq.top().e2;
        pq.pop();
        ll chg = b[(cr+1)%n]+b[(cr-1+n)%n];
        ll till = max({a[cr]});
        /* ll till = max({a[cr]}); */
        /* whatis(cr) */
        ll ile = (b[cr]-till)/chg;
        if(!ile) ++ile;
        /* ll ile = (b[cr]-till)/chg+bool((b[cr]-till)%chg); */
        /* if(!ile) REE(-1) */
        /* whatis(till) */
        /* whatis(ile) */
        res += ile;
        b[cr] -= ile*chg;
        /* while(b[cr] <= 0){ */
        /*     b[cr] += chg; */
        /*     --res; */
        /*     --ile; */
        /*     /1* if(ile == 1) REE(-1) *1/ */
        /*     /1* if(b[cr] > a[cr]) REE(-1) *1/ */
        /* } */
        /* if(ile <= 0) REE(-1) */
        /* whatis(b[cr]) */
        /* while(b[cr] >= b[(cr+1)%n] && b[cr] >= b[(cr-1+n)%n]){ */
        /*     ++res; */
        /*     b[cr] -= b[(cr+1)%n]+b[(cr-1+n)%n]; */
            if(b[cr] < a[cr]) REE(-1)
        /*     if(b[cr] == a[cr]) break; */
        /*     /1* if(b[cr] > a[cr]) *1/ */
        /*     /1*     pq.push({b[cr],cr}); *1/ */
        /* } */
        if(b[cr] > a[cr])
            pq.push({b[cr],cr});
    }
    cout << res << '\n';
}



Measured memory_bytes: 9328