#include <bits/stdc++.h>
using namespace std;

#define int long long

const int N=1e5+5;

int gcd(int x,int y)
{
	if(x>y)
		swap(x,y);

	if(x==0)
		return y;

	return gcd(y%x,x);
}

int lcm(int x,int y)
{
	return x/gcd(x,y)*y;
}

int x[N],y[N],val[N];
map <pair <int,int> ,bool> have;
map <pair <int,int> ,int> res;

pair <int,int> topair(int x,int y)
{
	if(x==0)
		return make_pair(0x3f3f3f3f,0);

	if(y==0)
		return make_pair(0,0);

	int GCD=gcd(abs(x),abs(y));
	x /= GCD, y /= GCD;
	if(x<0)
		x=-x, y=-y;
	return make_pair(x,y);
}

signed main()
{
	int n;
	cin >> n;
	if(n<=2)
	{
		printf("-1\n");
		return 0;
	}

	for(int i=1;i<=n;i++)
		scanf("%lld %lld",&x[i],&y[i]);

	for(int i=1;i<n;i++)
		x[i] -= x[n], y[i] -= y[n];
	n--;

	for(int i=1;i<=n;i++)
		have[topair(x[i],y[i])]=true;

	if(have.size()==1)
	{
		printf("-1\n");
		return 0;
	}

	for(int i=1;i<=n;i++)
	{
		int GCD=gcd(abs(x[i]),abs(y[i]));
		for(int j=1;j<=n;j++)
		{
			if(i==j)
				val[j]=0;
			else
				val[j]=abs((x[i]*y[j]-y[i]*x[j])/GCD);
		}

		int t=0;
		for(int j=1;j<=n;j++)
			t=gcd(t,val[j]);

		res[make_pair(y[i]/GCD,x[i]/GCD)]=t;
	}

	long long ans=1;
	for(auto x:res)
		ans=lcm(ans,x.second);
	printf("%lld\n",ans);
	return 0;
}