#warning Check FastIO
#ifdef ONLINE_JUDGE
#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#endif
#include <iostream>
#include <algorithm>
#include <climits>
#include <queue>
#include <cmath>
#include <map>
#include <set>
#include <random>
#include <chrono>
#include <iomanip>
#include <vector>
#include <fstream>
using namespace std;
#define vll vector<ll>
#define sll set<ll>
#define vstr vector<string>
#define ll long long
#define ld long double
#define supra main
#define pb push_back
#define add insert
#define rall(x) rbegin(x),rend(x)
#define all(x) (x).begin(),(x).end()
#define I ios_base::sync_with_stdio(false);
#define Hear cin.tie(NULL);
#define Shots cout.tie(NULL);
#define Ratatatata
#define bits_on(a) (__builtin_popcountll(a))
#define mx_pw2(a) (__builtin_ctzll(a))
mt19937 RNG(chrono::steady_clock::now().time_since_epoch().count());
#define SHUFFLE(v) shuffle(all(v), RNG);
const ll inf=LLONG_MAX;
void input(vll& a)
{
for(auto& i:a)
cin>>i;
}
void pyn(bool a)
{
cout<<(a?"YES":"NO")<<endl;
}
ll powmod(ll a,ll b,ll modulo)
{
if(b==0){
return 1;
}
ll temp=powmod(a,b/2,modulo);
if(b%2==0){
return (temp*temp)%modulo;
}
else{
return (a*((temp*temp)%modulo))%modulo;
}
}
bool Prime(ll n){
for (ll i = 2; i*i <= n; i++)
if (n % i == 0)
return false;
return (n>1);
}
const int N=3e5;
const int MX=401;
int par[N];
map<pair<int,int>,int>tp;
int nxp=1;
int mapping(int x,int y)
{
auto it=tp.find({x,y});
if(it==tp.end())
{
tp[{x,y}]=nxp;
par[nxp]=nxp;
nxp++;
}
return tp[{x,y}];
}
int comp=0;
int get(int x)
{
if(par[x]==x)return x;
return par[x]=get(par[x]);
}
void merge(int x,int y)
{
x=get(x);
y=get(y);
if(x==y)return;
comp--;
par[x]=y;
}
const int CP=100;
void solve()
{
ll n;
cin>>n;
for(int j=0;j<N;j++)
{
par[j]=j;
}
vector<pair<ll,ll>> a;
for(int i=0;i<n;i++)
{
ll x,y;
cin>>x>>y;
a.pb({x,y});
}
map<pair<ll,ll>,ll> lasp;
ll tot=0;
for(int x=-100;x<=100;x++)
{
for(int y=-100;y<=100;y++)
{
tot++;
for(int j=0;j<n;j++)
{
ll distx=a[j].first-x;
ll disty=a[j].second-y;
auto it=lasp.find({distx,disty});
if(it!=lasp.end())
merge((*it).second,mapping(x,y));
lasp[{distx,disty}]=mapping(x,y);
}
}
}
if(comp==0)
{
cout<<-1<<endl;
}
else
{
cout<<comp+tot<<endl;
}
}
int supra(){
I Hear Shots Ratatatata
ll tqwertyuiop=1;
for(int tp=1;tp<=tqwertyuiop;tp++)
{
// cout<<"Case #"<<tp<<": ";
solve();
}
return 0;
}
/*
Bro use only in a emergency
this is kind of hacking
#pragma GCC optimize("Ofast,unroll-loops")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,tune=native")
*/
