#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define lll __int128
#define pb push_back
const int N=1e5+5;
int n,a[N],b[N];lll p,x,y;
lll gcd(lll x,lll y) {return y?gcd(y,x%y):x;}
void wr(lll x) {if(x<10) {putchar(x+'0');return;}wr(x/10);putchar(x%10+'0');}
int main()
{
	scanf("%d",&n);for(int i=1;i<=n;++i) scanf("%d %d",&a[i],&b[i]);
	for(int i=1;i<n;++i) a[i]-=a[n],b[i]-=b[n];--n;x=a[n];y=b[n];
	for(int i=1;i<n;++i)
	{
		lll x1=a[i],y1=b[i];
		while(x1) {lll t=x/x1;x-=t*x1;y-=t*y1;if(p) y%=p;swap(x,x1);swap(y,y1);}
		p=gcd(p,y1);
	}if(!x || !p) printf("-1\n");else wr(abs(x*p));return 0;
}

answer.code: In function ‘int main()’:
answer.code:19:49: error: call of overloaded ‘abs(__int128)’ is ambiguous
   19 |         }if(!x || !p) printf("-1\n");else wr(abs(x*p));return 0;
      |                                              ~~~^~~~~
In file included from /usr/include/c++/13/cstdlib:79,
                 from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:42,
                 from answer.code:1:
/usr/include/stdlib.h:840:12: note: candidate: ‘int abs(int)’
  840 | extern int abs (int __x) __THROW __attribute__ ((__const__)) __wur;
      |            ^~~
In file included from /usr/include/c++/13/cstdlib:81:
/usr/include/c++/13/bits/std_abs.h:79:3: note: candidate: ‘constexpr long double std::abs(long double)’
   79 |   abs(long double __x)
      |   ^~~
/usr/include/c++/13/bits/std_abs.h:75:3: note: candidate: ‘constexpr float std::abs(float)’
   75 |   abs(float __x)
      |   ^~~
/usr/include/c++/13/bits/std_abs.h:71:3: note: candidate: ‘constexpr double std::abs(double)’
   71 |   abs(double __x)
      |   ^~~
/usr/include/c++/13/bits/std_abs.h:61:3: note: candidate: ‘long long int std::abs(long long int)’
   61 |   abs(long long __x) { return __builtin_llabs (__x); }
      |   ^~~
/usr/include/c++/13/bits/std_abs.h:56:3: note: candidate: ‘long int std::abs(long int)’
   56 |   abs(long __i) { return __builtin_labs(__i); }
      |   ^~~
answer.code:12:14: warning: ignoring return value of ‘int scanf(const char*, ...)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
   12 |         scanf("%d",&n);for(int i=1;i<=n;++i) scanf("%d %d",&a[i],&b[i]);
      |         ~~~~~^~~~~~~~~
answer.code:12:51: warning: ignoring return value of ‘int scanf(const char*, ...)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
   12 |         scanf("%d",&n);for(int i=1;i<=n;++i) scanf("%d %d",&a[i],&b[i]);
      |                                              ~~~~~^~~~~~~~~~~~~~~~~~~~~