#include <bits/stdc++.h>
 
using namespace std;
 
typedef long long ll;
typedef pair<ll,ll> P;
 
long long int INF = 3e18;
double Pi = 3.1415926535897932384626;
 
//vector<ll> G[550010];
//vector<P> tree[500010];
priority_queue <ll> pql;
priority_queue <P> pqp;
//big priority queue
priority_queue <ll,vector<ll>,greater<ll> > pqls;
priority_queue <P,vector<P>,greater<P> > pqps;
//small priority queue
//top pop
 
int dx[8]={1,0,-1,0,1,1,-1,-1};
int dy[8]={0,1,0,-1,1,-1,-1,1};
char dir[] = "DRUL";
//ll bit[500005];
//↓,→,↑,←
 
 
#define p(x) cout<<x<<"\n";
#define el cout<<endl;
#define pe(x) cout<<(x)<<" ";
#define ps(x) cout<<fixed<<setprecision(25)<<x<<endl;
#define pu(x) cout<<(x);
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define CLEAR(a) a = decltype(a)(); 
 
 
ll mod = 998244353;
/*
2000000011 is prime
2000000033 is prime
*/

ll rui(ll number1,ll number2){
 
    if(number2 == 0){
        return 1;
    }else{
        ll number3 = rui(number1,number2 / 2);
        number3 *= number3;
        number3 %= mod;
        if(number2%2==1){
            number3 *= number1;
            number3 %= mod;
        }
        return number3;
    }
}
ll gcd(ll number1,ll number2){
 
    if(number1 > number2){
        swap(number1,number2);
    }
    if(number1 == 0 || number1 == number2){
        return number2;
    }else{
        return gcd(number2 % number1,number1);
    }
}
void YES(bool condition){
 
    if(condition){
        p("YES");
    }else{
        p("NO");
    }
    return;
}
void Yes(bool condition){
 
    if(condition){
        p("Yes");
    }else{
        p("No");
    }
    return;
}

/*
ll fact[800005],rfact[800005];

void c3_init(){
    fact[0] = rfact[0] = 1;
    for(ll i=1; i<=800000; i++){
        fact[i] = (fact[i-1]*i) % mod;
    }
    rfact[800000] = rui(fact[800000],mod - 2);
    for(ll i=800000; i>=1; i--){
       rfact[i-1] = rfact[i] * i;
       rfact[i-1] %= mod;
    }
    return;}
ll c3(ll n,ll r){
    return (((fact[n] * rfact[r]) % mod) * rfact[n-r]) % mod;}
*/
 
ll n,m,num,sum,a,b,c,d,e,g,h,w,i,j,q,r;
ll k,ans;
ll x[500005],y[500005],z[500005];
char s[500005];
bool ok_table[500005];
ll ok;
bool dame ;
vector <ll> v;

void push_check(ll i){
    if(i == 0){
        if((y[0] > x[0]) && (y[i] > y[i+1] + y[n-1])){
            v.pb(i);
        }
        return;
    }

    if(i == n-1){
        if((y[i] > x[i]) && (y[i] > y[i-1] + y[0])){
            v.pb(i);
        }
        return;
    }
    if((y[i] > (y[i-1] + y[i+1])) && (y[i] > x[i])){
        v.pb(i);
    }
    return;
}

int main(){
    cin >> n;
    
    for(i=0;i<n;i++){
        cin >> x[i];
    }
    for(i=0;i<n;i++){
        cin >> y[i];
    }
    for(int i=0;i<n;i++){
        push_check(i);
    }
    for(i=0;i<v.size();i++){
       // pe(v[i]);
    }
    for(i=0;i<n;i++){
        if(x[i] == y[i]){
            ok_table[i] = true;
            ok++;
        }
    }
    //el;
    while(!v.empty()){
        ll i = v.back();
      //  p(i);
        v.pop_back();
        ll div,deka;
        if(i == 0){
            div = y[n-1] + y[1];
        }else if(i == n - 1){
            div = y[i-1] + y[0];
        }else{
            div = y[i-1] + y[i+1];
        }
        ll num = y[i] - x[i];
        ans += num / div;
        y[i] -= div * (num / div);
        if(y[i] == x[i] && !ok_table[i]){
            ok++;
            ok_table[i] = true;
        }
        if(ok == n)break;
        if(y[i] < x[i] || num <= 0){
            dame = true;
            break;
        }else{
            ll i1,i2;
            if(i == 0){
                i1 = n - 1;
                i2 = 1;
            }else if(i == n - 1){
                i1 = n - 2;
                i2 = 0;
            }else{
                i1 = i - 1;
                i2 = i + 1;
            }
            push_check(i1);
            push_check(i2);
            //push_check(i);
        }
        for(int i=0;i<n;i++){
            //pe(y[i]);
        }
        //el;
        bool end = true;
    }
    for(i=0;i<n;i++){
        if(x[i] != y[i])dame = true;
    }
    if(!dame){
        p(ans);
    }else{
        p(-1);
    }
    
    /*
    p(n);
    for(i=0;i<n;i++){
        pe(1);
    }
    el;
    for(i=0;i<n;i++){
        pe(99921128 + i % 7);
    }
    el;
    */
    
    
    
    return 0;
}






Measured memory_bytes: 9592