#include<bits/stdc++.h>
using namespace std;

typedef long long ll;
const int N=200005;
ll a[N],b[N];
int n;
struct node{
	int id;
	ll val;
	bool operator <(const node &x)const{
		return val<x.val;
	}
};
priority_queue<node> myline;
int main(){
	scanf("%d",&n);
	for(int i=1;i<=n;i++){scanf("%lld",&a[i]);}
	for(int i=1;i<=n;i++){scanf("%lld",&b[i]);myline.push((node){i,b[i]});}
    bool flag=false;
    ll ans=0;
    while(!myline.empty()){
		node head=myline.top();myline.pop();
		int dd=head.id;
	//	printf("b[%d]=%d,a[%d]=%d\n",dd,b[dd],dd,a[dd]);
		if(a[dd]==b[dd]) continue;
		int l,r;
		if(dd==1) l=n;else l=dd-1;
		if(dd==n) r=1;else r=dd+1; 
		//b[dd]-=b[l];b[dd]-=b[r];
		if(b[dd]-b[l]-b[r]<a[dd]) {puts("-1");flag=true;break;}
		ll tmp=(b[dd]-a[dd])/((b[l]+b[r]));
		b[dd]-=tmp*(b[l]+b[r]);
		ans+=tmp;
		if(b[dd]<a[dd]) {puts("-1");flag=true;break;}
		myline.push((node){dd,b[dd]});
	}
	if(!flag) printf("%lld",ans);
}