#include <bits/stdc++.h>
using namespace std;
using ll = __int128; using pii = pair<ll,ll>;
ll gcd2(ll a, ll b) {
if (a==0 || b==0) {
return max(labs(a),labs(b));
}
return gcd(labs(a),labs(b));
}
ll cpr(pii p1, pii p2) {
return (p1.first*p2.second-p2.first*p1.second);
}
inline ll fmod(ll x, ll MOD) {
return (x+MOD*(2-x/MOD))%MOD;
}
inline pii fmod(pii p0, ll MOD) {
return {fmod(p0.first,MOD),fmod(p0.second,MOD)};
}
ll inv(ll x, ll MOD) {
assert(MOD!=0);
if (MOD<0) {
MOD=-MOD;
}
x = fmod(x,MOD);
array<ll,3> a = {x,1,0};
array<ll,3> b = {MOD,0,1};
while (b[0]!=1) {
if (a[0]>b[0]) {
swap(a,b);
} else {
ll k = b[0]/a[0];
for (ll i=0;i<3;i++) {
b[i]-=k*a[i];
}
}
}
return fmod(b[1],MOD);
}
pii fix(pii p1, pii p2) { //assuming cpr = 0, adjust both
assert(cpr(p1,p2)==0);
if (p1.first==0 && p1.second==0) {
return p2;
}
if (p2.first==0 && p2.second==0) {
return p1;
}
if (p1.first==0 && p2.first==0) {
return {0LL,gcd2(p1.second,p2.second)};
}
if (p1.second==0 && p2.second==0) {
return {gcd2(p1.first,p2.first),0LL};
}
ll a = gcd2(p1.first,p2.first);
return {a,(p1.second*a)/p1.first};
}
ll ans = 0;
ll nvec = 0;
pii p0,p1;
void flip() {
if (nvec==2) {
swap(p0,p1);
}
}
void anl() {
if (ans==-1) {
if (nvec==2) {
if (cpr(p1,p0)==0) {
p1 = fix(p1,p0);
nvec=1;
}
}
return;
}
if (nvec==0) {
return;
}
if (nvec==1) {
p0 = fmod(p0,ans);
if (p0.first==0 && p0.second==0) {
nvec = 0;
}
return;
}
if (nvec==2) {
p0 = fmod(p0,ans);
if (p0.first==0 && p0.second==0) {
nvec = 1;
swap(p0,p1);
anl();
return;
}
p1 = fmod(p1,ans);
if (p1.first==0 && p1.second==0) {
nvec = 1;
anl();
return;
}
if (cpr(p1,p0)==0) {
p1 = fix(p1,p0);
nvec = 1;
anl();
return;
}
assert(ans%labs(cpr(p1,p0))==0);
if (labs(cpr(p1,p0))<ans) {
ans = labs(cpr(p1,p0));
anl();
}
return;
}
}
void fz0(pii p2) {
if (nvec==0) {
p0 = p2; return;
}
if (nvec==1) {
if (cpr(p0,p2)==0) {
p0 = fix(p0,p2);
return;
} else {
p1 = p2;
nvec = 2;
if (ans==-1) {
ans = labs(cpr(p0,p1));
} else {
ans = gcd2(labs(cpr(p0,p1)),ans);
}
return;
}
}
if (nvec==2) {
if (labs(cpr(p0,p2))%ans!=0) {
ans = gcd2(cpr(p0,p2),ans);
p1 = p2;
return;
}
if (labs(cpr(p1,p2))%ans!=0) {
ans = gcd2(cpr(p1,p2),ans);
p0 = p2;
return;
}
}
}
void fz(pii p2) {
anl();
if (ans!=-1) {
p2 = fmod(p2,ans);
}
if (p2.first==0 && p2.second==0) {
return;
}
fz0(p2);
anl();
}
int main() {
ios_base::sync_with_stdio(false); cin.tie(0);
long long N; cin >> N;
if (N<=2) {
cout << "-1\n";
exit(0);
}
long long x0,y0; cin >> x0 >> y0;
vector<pii> v0;
for (ll i=0;i<(N-1);i++) {
long long x1,y1; cin >> x1 >> y1;
v0.push_back({x1-x0,y1-y0});
}
ll ansS = 0;
for (ll i=1;i<(N-1);i++) {
ansS = gcd2(ansS,cpr(v0[0],v0[i]));
}
if (ansS == 0) {
cout << "-1\n"; exit(0);
}
ans = ansS;
for (pii p2: v0) {
while(1) {
ll ansc = ans;
pii p0c = p0; pii p1c = p1;
fz(p2);
flip();
fz(p2);
fz(p1);
flip();
fz(p1);
fz(p0);
flip();
fz(p0);
ll ansc2 = ans;
assert(ansc%ansc2==0);
if (ansc2==ansc) {
break;
}
}
}
cout << (long long) ans << "\n";
}
