#include<iostream>
#include<queue>
using namespace std;
int N_MAX = 200000;
typedef pair<long long,int> P;
int main()
{
  int n,i,j,k;
  long long t,res=0;
  long long a[N_MAX],b[N_MAX];
  P p;
  priority_queue<P> q;
  cin >> n;
  for(i=0;i<n;i++)
    cin >> a[i];
  for(i=0;i<n;i++){
    cin >> b[i];
    p.first=b[i];
    p.second=i;
    q.push(p);
  }
  i=n-1;j=0;k=1;
  while(!q.empty()){
    p=q.top(); q.pop();
    j=p.second;
    i=(j+n-1)%n;
    k=(j+1)%n;
    if(b[j]==a[j])
      continue;
    if(b[j]-b[i]-b[k]<a[j]){
      cout << "-1" << endl;
      return 0;
    }
    t=(b[j]-a[j])/(b[i]+b[k]);
    b[j]-=(b[i]+b[k])*t;
    p.first=b[j];
    q.push(p);
    res+=t;
  }
  for(i=0;i<n;i++)
    if(a[i]!=b[i]){
      cout << "-1" << endl;
      return 0;
    }
  cout << res << endl;
  return 0;
}