#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
using ll=long long;

struct point{
    ll x,y;
};

struct edge{
    int A,B,W;
    ll D;
    edge(int a,int b,int w,ll d){
        A=a;B=b;W=w;D=d;
    }
};

int n;
vector <point> v(1e3);
vector <edge> ed;
vector <int> p(2e3,0);
vector <int> sz(2e3,1);

int sgn(ll num){
    return (num>0)-(num<0);
}

int turn(point a, point b,point c){
    return sgn((c.y-a.y)*(b.x-a.x)-(b.y-a.y)*(c.x-a.x));
}

int intersection(point a,point b){
    point c,d;
    c.x=c.y=0;
    d.x=1;d.y=1e9+1;
    if (turn(a,b,c)*turn(a,b,d)>-1) return 0;
    if (turn(c,d,a)*turn(c,d,b)>-1) return 0;
    return 1;
}

ll dist(point a, point b){
    return (a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y);
}

bool srt(edge e,edge f){
    return (e.D<f.D?true:false);
}

int holvan(int a){
    return (a==p[a]?a:p[a]=holvan(p[a]));
}

void unio(int a,int b){
    a=holvan(a);
    b=holvan(b);
    if (a==b) return;
    if (sz[a]>sz[b]) swap(a,b);
    p[a]=b;
    sz[b]+=sz[a];
}

bool UNIO(edge e){
    if (e.W){
        unio(e.A,e.B+n);
        unio(e.A+n,e.B);
    }else{
        unio(e.A,e.B);
        unio(e.A+n,e.B+n);
    }
    return (holvan(e.A)==holvan(e.A+n)?true:false);
}

int main(){
    cin >> n;
    for (int i=0;i<n;i++){
        cin >> v[i].x >> v[i].y;
        for (int j=0;j<i;j++){
            ed.push_back(edge(i,j,intersection(v[i],v[j]),dist(v[i],v[j])));
        }
    }
    sort(ed.begin(),ed.end(),srt);
    for (int i=0;i<2*n;i++) p[i]=i;
    for (edge e : ed){
        if (UNIO(e)){
            cout << e.D;
            return 0;
        }
    }
    cout << -1;
}