#include<bits/stdc++.h>
using namespace std;
#define x first
#define y second
#define int long long
#define all(x) x.begin(),x.end()
#define pii pair<int,int>
#define rz resize
#define pb emplace_back
#define LCBorz ios_base::sync_with_stdio(false);cin.tie(0);
#define endl '\n'
mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());
const int INF=9e18;
const int mod=1e9+7;
const int N=200005;
const int K=20;
const int C=2000005;
int gcd(int a,int b){
return abs(__gcd(a,b));
}
int32_t main(){
LCBorz;
int n;cin>>n;
if(n<=2){
cout<<-1<<endl;
return 0;
}
vector<pair<int,int>> v(n),v1(n);
for(int i=0;i<n;i++){
int a,b;cin>>a>>b;
v[i]={a,b};
}
sort(all(v));
for(int i=1;i<n;i++){
v[i].x-=v[0].x;
v[i].y-=v[0].y;
}
int ans=-1;
auto solve=[&](int i,int j)->void {
if(v[i].y==0&&v[j].y==0){
return;
}
if(v[i].y==0){
ans=(ans==-1?v[i].x:gcd(v[i].x,ans));
return;
}
if(v[j].y==0){
ans=(ans==-1?v[j].x:gcd(v[j].x,ans));
return;
}
int r1=v[j].y/gcd(v[i].y,v[j].y);
int t=v[i].y*r1;
int t1=t/v[j].y;
int x1=abs(v[i].x*r1-v[j].x*t1);
if(x1!=0)ans=(ans==-1?x1:gcd(ans,x1));
};
for(int i=0;i<10000000;i++){
int g1=rnd()%(n-1)+1;
int g2=rnd()%(n-1)+1;
solve(g1,g2);
}
int g1=-1;
for(int i=1;i<n;i++){
if(v[i].y==0)continue;
g1=(g1==-1?abs(v[i].y):gcd(g1,v[i].y));
}
//cout<<ans<<' '<<g1<<endl;
cout<<(ans==-1?-1:ans*g1)<<endl;
return 0;
}
