#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using i128 = __int128_t;
i128 abs128(i128 x){
return x < 0 ? -x : x;
}
i128 gcd128(i128 a, i128 b){
a = abs128(a);
b = abs128(b);
while(b != 0){
i128 r = a % b;
a = b;
b = r;
}
return a;
}
ll egcd(ll a, ll b, ll &x, ll &y){
if(b == 0){
x = 1;
y = 0;
return a;
}
ll x1, y1;
ll g = egcd(b, a % b, x1, y1);
x = y1;
y = x1 - (a / b) * y1;
return g;
}
void print128(i128 x){
if(x == 0){
cout << 0;
return;
}
if(x < 0){
cout << '-';
x = -x;
}
string s;
while(x > 0){
s.push_back('0' + x % 10);
x /= 10;
}
reverse(s.begin(), s.end());
cout << s;
}
int main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
int N;
cin >> N;
vector<ll> x(N), y(N);
for(int i = 0; i < N; i++){
cin >> x[i] >> y[i];
}
ll bx = x[0];
ll by = y[0];
ll p = 0;
i128 t = 0;
i128 h = 0;
for(int i = 1; i < N; i++){
ll X = x[i] - bx;
ll Y = y[i] - by;
if(X == 0){
h = gcd128(h, (i128)Y);
if(p > 0 && h > 0){
t %= h;
if(t < 0) t += h;
}
continue;
}
if(p == 0){
if(X < 0){
p = -X;
t = -(i128)Y;
}
else{
p = X;
t = Y;
}
if(h > 0){
t %= h;
if(t < 0) t += h;
}
continue;
}
ll ax = llabs(X);
ll newp = gcd(p, ax);
ll A, B;
egcd(p, ax, A, B);
if(X < 0) B = -B;
i128 vertical =
((i128)X / newp) * t - ((i128)p / newp) * Y;
h = gcd128(h, vertical);
i128 newt = (i128)A * t + (i128)B * Y;
p = newp;
t = newt;
if(h > 0){
t %= h;
if(t < 0) t += h;
}
}
if(p > 0 && h > 0){
print128((i128)p * h);
cout << '\n';
}
else{
cout << -1 << '\n';
}
}
