#include <bits/stdc++.h>
using namespace std;

int main() {
  cin.tie(nullptr);
  ios::sync_with_stdio(false);
  int n;
  cin >> n;
  vector<double> x(n), y(n);
  for (int i = 0; i < n; ++i) {
    cin >> x[i] >> y[i];
  }
  auto d = [&](double cx, double cy) {
    double res = 0;
    for (int i = 0; i < n; ++i) {
      res = max(res, hypot(x[i] - cx, y[i] - cy));
    }
    return res;
  };
  auto fn = [&](double a) {
    double ly = 0, ry = 1000;
    for (int _ = 100; _--; ) {
      double mly = (2 * ly + ry) / 3, mry = (ly + 2 * ry) / 3;
      if (d(a, mly) < d(a, mry)) {
        ry = mry;
      } else {
        ly = mly;
      }
    }
    return d(a, ly);
  };
  double lx = 0, rx = 1000;
  for (int _ = 100; _--; ) {
    double mlx = (2 * lx + rx) / 3, mrx = (lx + 2 * rx) / 3;
    if (fn(mlx) < fn(mrx)) {
      rx = mrx;
    } else {
      lx = mlx;
    }
  }
  cout << fixed << setprecision(20);
  cout << fn(lx) << '\n';
}
