#include <bits/stdc++.h>
/*
Have a tiling that can be translated by any amount
*/
long long gcd(long long a,long long b){
while(a!=0&&b!=0){
a%=b;
std::swap(a,b);
}
return a+b;
}
std::pair<int,int> getmuls(int a,int b){//extended Euclidean algorithm
int aina=1,ainb=0,bina=0,binb=1;
while(a!=0&&b!=0){
int adb=a/b;
aina-=adb*ainb;
bina-=adb*binb;
a=a%b;
if(a==0)break;
int bda=b/a;
ainb-=bda*aina;
binb-=bda*bina;
b=b%a;
}
return {aina+ainb,bina+binb};
}
int main(){
std::ios::sync_with_stdio(0);
std::cin.tie(0);
int n;
std::cin>>n;
long long ia,ib;
std::cin>>ia>>ib;
long long xrep=0,yrep=0,yoff=0;
for(int i=1;i<n;i++){
long long a,b;
std::cin>>a>>b;
a-=ia,b-=ib;
if(b==0&&yrep==0){//division by 0
xrep=gcd(a,xrep);
}else{
std::pair<int,int> nums=getmuls(b,yrep);
long long ngcd=nums.first*b+nums.second*yrep;
long long nxrep=std::abs((a*yrep-yoff*b)/ngcd);
xrep=gcd(xrep,nxrep);
yoff=nums.first*a+nums.second*yoff;
yrep=ngcd;
if(xrep!=0)yoff%=xrep;
}
}
long long result=std::abs(xrep*yrep);
std::cout<<(result==0?-1:result)<<'\n';
}
