#include <bits/stdc++.h>

#define rep(i, n) for(int (i) = 0; i < (n); ++(i))

typedef long long ll;
const ll MOD = 1e9 + 7;

struct Point {
  double x, y;
};

double dist(const Point &a, const Point &b) {
  double dx = a.x - b.x;
  double dy = a.y - b.y;
  return std::sqrt(dx * dx + dy * dy);
}

int main() {
  int N;
  std::cin >> N;

  std::vector<Point> ps(N);
  rep(i, N) {
    std::cin >> ps[i].x >> ps[i].y;
  }

  auto f = [&](double x, double y) {
    double ret = 0;
    rep(i, N) {
      ret = std::max(ret, dist(Point{x, y}, ps[i]));
    }
    return ret;
  };

  const double EPS = 1e-10;
  auto g = [&](double x) {
    double l = 0;
    double r = 1000;
    while(r - l > EPS) {
      double ml = (l*2 + r) / 3;
      double mr = (l + r*2) / 3;
      if(f(x, ml) > f(x, mr)) {
        l = ml;
      } else {
        r = mr;
      }
    }
    return f(x, l);
  };

  double l = 0;
  double r = 1000;
  while(r - l > EPS) {
    double ml = (l*2 + r) / 3;
    double mr = (l + r*2) / 3;
    if(g(ml) > g(mr)) {
      l = ml;
    } else {
      r = mr;
    }
  };

  std::cout << std::fixed << std::setprecision(10) << g(l) << '\n';
}