#include <bits/stdc++.h>
#define int long long
#define pii pair<int,int>
#define ff first
#define ss second
using namespace std;
int mcd(int a,int b)
{
if (a>b)swap(a,b);
if (a==0)return b;
a = abs(a),b = abs(b);
return __gcd(a,b);
}
int exg(int a, int b, int& x, int& y) {
if (b == 0) {
x = 1;
y = 0;
return a;
}
int x1, y1;
int d = exg(b, a % b, x1, y1);
x = y1;
y = x1 - y1 * (a / b);
return d;
}
signed main()
{
int n;
cin >> n;
vector<pii> v(n);
for (int i = 0; i < n ;i++)
cin >> v[i].ff >> v[i].ss;
for (int i = n-1; i >= 0; i--)
v[i].ff-=v[0].ff,v[i].ss-=v[0].ss;
int x = (v[1].ss==0?v[1].ff:0), y = v[1].ss,px = v[1].ff,py = v[1].ss,up = v[1].ss;
for (int i = 2; i < n; i++)
{
int add = 0;
if (v[i].ss == 0)
add = v[i].ff;
else if (py!=0)
{
int lc = v[i].ss*py/mcd(v[i].ss,py);
int c1 = lc/py;
int c2 = lc/v[i].ss;
add = c2*v[i].ff - c1*px;
}
x = mcd(x,add);
int k1,k2;
y = exg(py,v[i].ss,k1,k2);
py = y;
px = k1*px + k2*v[i].ff;
if(x)
{
int dum = 1000;
while(dum*x < abs(px))
dum*=2;
px+=dum*x;
px%=x;
}
}
if (x*y == 0)
cout << -1;
else
cout << abs(x*y);
return 0;
}
