#include <bits/stdc++.h>
using namespace std;
using ll = long long;
vector<int> p, r;
int n;
int get(int v)
{
    return p[v] == 0 ? v : p[v] = get(p[v]);
}
void unio(int a, int b)
{
    a = get(a);
    b = get(b);
    if(a != b)
    {
        if(r[a] < r[b]) swap(a, b);
        p[b] = a;
        if(r[a] == r[b]) r[a]++;
    }
}
struct val
{
    ll a, b, d;
};
bool insc(ll xa, ll xb, ll ya, ll yb)
{
    if(xb != xa)
    {
        long double b = (yb - ya) / (xb - xa);
        if(b == 0) return 0;
        long double x = xa + (-ya / b);
        return x > 0;
    }
    return xa > 0;
}
int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cin >> n;
    p.resize(2 * n + 1);
    r.resize(2 * n + 1);
    vector<ll> x(n + 1), y(n + 1);
    vector<val> e;
    for(int i = 1; i <= n; i++)
    {
        cin >> x[i] >> y[i];
        for(int j = 1; j < i; j++)
        {
            ll dx = x[i] - x[j], dy = y[i] - y[j];
            e.push_back({j, i, dx * dx + dy * dy});
        }
    }
    sort(e.begin(), e.end(), [](val a, val b)
    {
        return a.d < b.d;
    });
    for(auto [a, b, d] : e)
    {
        bool g = insc(x[a], x[b], y[a], y[b]);
        if(g)
        {
            unio(a, b + n);
            unio(a + n, b);
        }
        else
        {
            unio(a, b);
            unio(a + n, b + n);
        }
        if(get(a) == get(a + n))
        {
            cout << d << "\n";
            return 0;
        }
    }
    cout << "-1\n";
}