#include<bits/stdc++.h>
#define N 300050
#define ll long long
#define pii pair<int,int>
#define fi first
#define se second
using namespace std;
const int mx=1e6;
int n,x[N],y[N],tt1,tt2;
pii a[N];int b[N];
vector<pii>vec[2000005];
ll gcd(ll a,ll b){
	if(!a|!b)return a+b;
	int az=__builtin_ctzll(a);
	int bz=__builtin_ctzll(b);
	int z=min(az,bz);
	a>>=az,b>>=bz;
	while(a!=b){
		ll d=b-a;
		az=__builtin_ctzll(d);
		b=min(a,b),a=abs(d)>>az;
	}
	return a<<z;
}
const int Mx=2e6;
int main(){
	ios::sync_with_stdio(0);
	cin>>n;
	for(int i=1;i<=n;++i)cin>>x[i]>>y[i];
	int f=1;
	for(int i=2;i<=n;++i){
		if(x[i]==x[1])b[++tt2]=abs(y[i]-y[1]);    
		else{
			if(y[i]!=y[1])f=0;
			if(x[i]<x[1])a[++tt1]=make_pair(x[1]-x[i],y[1]-y[i]);
			else a[++tt1]=make_pair(x[i]-x[1],y[i]-y[1]);
		}
	}
	if(!tt1)puts("-1"),exit(0);
	if(tt1==1&&!tt2)puts("-1"),exit(0);
	if(!tt2&&f)puts("-1"),exit(0);
	ll g=0,g1=0;for(int i=1;i<=tt2;++i)g=gcd(g,b[i]);
	for(int i=1;i<=tt1;++i)g1=gcd(g1,a[i].fi),vec[a[i].fi].push_back(a[i]);
	for(int i=1;i<=Mx;++i){
		int ct=0;ll G=0;
		pii lst=make_pair(0,0);
		for(int j=i;j<=Mx;j+=i)
			for(auto v:vec[j]){
				if(!ct){++ct,lst=v;continue;}
				ll x=1ll*lst.fi*v.se-1ll*lst.se*v.fi;
				if(x<0)x=-x;lst=v,++ct;
				if(!G){G=x;continue;}
				if(!x||G%x==0)continue;
				G=gcd(G,x);
			}
		if(ct<=1)continue;
		g=gcd(g,G/(ll)(i));
	}
	if(!g||!g1)puts("-1"),exit(0);
	cout<<g*g1<<endl;
	return 0;
}