#include<bits/stdc++.h>
#define int long long
#define reg register
inline int read(){
	int k=1,x=0;char ch=getchar();
	while (ch<'0'||ch>'9') {if (ch=='-') k=-1; ch=getchar();}
	while (ch>='0'&&ch<='9') x=(x<<3)+(x<<1)+ch-48,ch=getchar();
	return k*x;
}
const int N=2e6+10,V=400;
int n,prex[N],sufx[N],prey[N],sufy[N];
struct Node{
	int x,y;
	inline int operator^(const Node &rhs)const{return x*rhs.y-y*rhs.x;}
	inline Node operator-(const Node &rhs)const{return {x-rhs.x,y-rhs.y};}
}p[N],a[N];
inline int cabs(reg int x){return x<0?-x:x;}
signed main(){
	n=read();
	for (reg int i=1;i<=n;i++) p[i].x=read(),p[i].y=read();
	for (reg int i=1;i<n;i++) a[i]=p[i]-p[i+1];
	for (reg int i=1;i<n;i++) prex[i]=std::__gcd(prex[i-1],a[i].x),prey[i]=std::__gcd(prey[i-1],a[i].y);
	for (reg int i=n-1;i;i--) sufx[i]=std::__gcd(sufx[i+1],a[i].x),sufy[i]=std::__gcd(sufy[i+1],a[i].y); 
	reg int g=0;
	for (reg int i=1;i<n;i++){
		reg int g1=a[i].x*std::__gcd(prey[i-1],sufy[i+1]);
		reg int g2=a[i].y*std::__gcd(prex[i-1],sufx[i+1]);
		g=std::__gcd(std::__gcd(g,g1),g2);
	}
	printf("%lld",g?g:-1);
	return 0;
}