#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ld long double
#define show(x,y) cout << y << " " << #x << endl;
#define show2(x,y,i,j) cout << y << " " << #x << " " << j << " " << #i << endl;
#define show3(x,y,i,j,p,q) cout << y << " " << #x << " " << j << " " << #i << " " << q << " " << #p << endl;
#define show4(x,y) for(auto it:y) cout << it << " "; cout << #x << endl;
typedef pair<int,int>pii;
typedef pair<int,pii>pi2;
void solve(){
int n;
cin >> n;
pii arr[n];
for(int x=0;x<n;x++){
cin >> arr[x].first >> arr[x].second;
}
vector<int>diff;
vector<int>diff2;
for(int x=0;x<n;x++){
for(int y=0;y<n;y++){
pii hold=arr[x]; //higher
pii hold2=arr[y];
if(arr[x].second<arr[y].second) swap(hold,hold2);
if(hold.second==hold2.second){
diff.push_back(abs(hold.first-hold2.first));
}
else if(hold2.first<hold.first){
diff.push_back(abs(hold.first-hold2.first));
diff2.push_back(abs(hold.second-hold2.second)+1);
}
else if(hold2.first==hold.first){
diff2.push_back(abs(hold.second-hold2.second));
}
else if(hold2.first>hold.first){
diff.push_back(abs(hold.first-hold2.first));
diff2.push_back(abs(hold.second-hold2.second)+1);
}
}
}
if(diff.size()==0||diff2.size()==0){
cout << -1;
return;
}
int hold=diff[0];
int hold2=diff2[0];
for(auto it:diff){
hold=__gcd(hold,it);
}
for(auto it:diff2){
hold2=__gcd(hold2,it);
}
cout << hold*hold2 << "\n";
}
int32_t main(){
ios::sync_with_stdio(0);
cin.tie(0);
int t=1;
//cin >> t;
//freopen("in.txt","r",stdin);
while(t--){
solve();
}
}
