#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define endl '\n'

int n;
double x[1005], y[1005], X, Y, d, e;
double dist(double a, double b) {
    return a*a + b*b;
}
int main() {

    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> x[i] >> y[i];
        X += x[i]; Y += y[i];
    }
    X /= n; Y /= n;
    double P = 0.1;
    for (int i = 0; i < 30000; i++) {
        int f = 0;
        d = dist(X - x[0], Y - y[0]);
        for (int j = 1; j < n; j++) {
            e = dist(X - x[j], Y - y[j]);
            if (d < e) { d = e; f = j; }
        }
        X += (x[f] - X)*P;
        Y += (y[f] - Y)*P;
        P *= 0.999;
    }
    cout << fixed << setprecision(10) << sqrt(d) << endl;
}



