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

int n;
vector<int> X, Y;

double g(double x, double y) {
    double ma = 0;
    rep(i, n) {
        ma = max(ma, sqrt((X[i] - x) * (X[i] - x) + (Y[i] - y) * (Y[i] - y)));
    }
    return ma;
}

double f(double x) {
    double low_y = 0, high_y = 1000;
    while (high_y - low_y > 1e-8) {
        double c1 = (low_y * 2 + high_y) / 3, c2 = (high_y * 2 + low_y) / 3;
        if (g(x, c1) < g(x, c2)) high_y = c2;
        else low_y = c1;
    }
    return g(x, high_y);
}

int main() {
    cin >> n;
    rep(i, n) {
        int a, b;
        cin >> a >> b;
        X.push_back(a), Y.push_back(b);
    }
    double low_x = 0, high_x = 1000;
    while(high_x - low_x > 1e-8) {
        double c1 = (low_x * 2 + high_x) / 3, c2 = (high_x * 2 + low_x) / 3;
        if (f(c1) < f(c2)) high_x = c2;
        else low_x = c1;
    }
    cout << fixed << setprecision(8) << f(low_x) << endl;
    return 0;
}
