// Slower C++ solution:
//#pragma GCC optimize("O3")

//#pragma GCC target("avx")



#include <algorithm>

#include <cmath>

#include <functional>

#include <iomanip>

#include <iostream>

#include <iterator>

#include <list>

#include <map>

#include <numeric>

#include <queue>

#include <random>

#include <set>

#include <sstream>

#include <string>

#include <type_traits>

#include <unordered_map>

#include <unordered_set>

#include <utility>

#include <vector>



using namespace std;



// Types

using ll = long long int;

using str = string;

template <class T> using u_set = unordered_set<T>;

template <class K, class V> using u_map = unordered_map<K, V>;

template <class V> using graph = u_map<V, u_set<V>>;

template <class F,

          typename enable_if<is_function<F>::value, nullptr_t>::type = nullptr>

using fun = function<F>;



namespace io {

// Input

using IS = istream;

IS &in(IS &);

IS &in(IS &i) { return i; }

template <class T, class... Ts> IS &in(IS &i, T &a, Ts &... as) {

  return in(i >> a, as...);

}

template <class V> IS &operator>>(IS &i, vector<V> &a) {

  for_each(a.begin(), a.end(), [&i](auto &e) { i >> e; });

  return i;

}

template <class F, class S> IS &operator>>(IS &i, pair<F, S> &p) {

  return in(i, p.first, p.second);

}

template <class... Ts, size_t... I>

IS &tuple_in(IS &i, tuple<Ts...> &t, index_sequence<I...>) {

  return in(i, get<I>(t)...);

}

template <class... Ts> IS &operator>>(IS &i, tuple<Ts...> &t) {

  return tuple_in(i, t, make_index_sequence<sizeof...(Ts)>());

}

// Output

using OS = ostream;

OS &out(OS &o) { return o << endl; }

template <class T> OS &out(OS &o, T const &a) { return o << a << endl; }

template <class T, class... Ts> OS &out(OS &o, T const &a, Ts const &... as) {

  return out(o << a << " ", as...);

}

template <class F, class S> OS &operator<<(OS &o, pair<F, S> const &p) {

  return o << p.first << ":" << p.second;

}

template <class... Ts> OS &args_out(OS &o, Ts const &... ts);

OS &args_out(OS &o) { return o; }

template <class T> OS &args_out(OS &o, T const &t) { return o << t; }

template <class T0, class T1, class... Ts>

OS &args_out(OS &o, T0 const &t0, T1 const &t1, Ts const &... ts) {

  return args_out(o << t0 << ",", t1, ts...);

}

template <class... Ts, size_t... I>

OS &tuple_out(OS &o, tuple<Ts...> const &t, index_sequence<I...>) {

  return args_out(o, get<I>(t)...);

}

template <class... Ts> OS &operator<<(OS &o, tuple<Ts...> const &t) {

  return tuple_out(o << "(", t, make_index_sequence<sizeof...(Ts)>()) << ")";

}

template <

    class C,

    class T = typename iterator_traits<typename C::iterator>::value_type,

    typename enable_if<!is_same<C, str>::value, nullptr_t>::type = nullptr>

OS &operator<<(OS &o, C const &a) {

  return a.empty() ? (o << "[]") : ([&o, &a]() -> OS & {

    o << "[" << *a.begin();

    for_each(next(a.begin()), a.end(), [&o](auto const &e) { o << "," << e; });

    return o << "]";

  }());

}

} // namespace io

auto input = [](auto &... a) { io::in(cin, a...); };

auto print = [](auto const &... a) { io::out(cout, a...); };

#ifdef JUMPAKU_DEBUG

auto dump = [](auto const &... a) { io::out(cerr, a...); };

#else

auto dump = [](auto const &...) {};

#endif



// Hash

namespace hashcode {

template <class... Ts> size_t hash_args(size_t h, Ts const &... ts);

size_t hash_args(size_t h) { return h; }

template <class T, class... Ts>

size_t hash_args(size_t h, T const &t, Ts const &... ts) {

  return hash_args(((h << 10) - h + hash<T>{}(t)), ts...);

}

template <class... Ts, size_t... I>

size_t hash_tuple(tuple<Ts...> const &t, index_sequence<I...>) {

  return hash_args(17, get<I>(t)...);

}

} // namespace hashcode

namespace std {

template <class... Ts> struct hash<tuple<Ts...>> {

  size_t operator()(tuple<Ts...> const &t) const {

    return hashcode::hash_tuple(t, index_sequence_for<Ts...>());

  }

};

} // namespace std



// Range

vector<ll> range(ll const &begin, ll const &end) {

  vector<ll> ret(max(0LL, end - begin));

  iota(ret.begin(), ret.end(), begin);

  return ret;

}

vector<ll> range(ll const &end) { return range(0, end); }

template <class T = ll> vector<T> vec(size_t n, T &&init = T()) {

  return vector<T>(n, init);

}



ll bisect(ll ng, ll ok, fun<bool(ll)> const &is_ok) {

  while (ok - ng > 1) {

    dump(ng, ok);

    ll m = ng + (ok - ng) / 2;

    (is_ok(m) ? ok : ng) = m;

  }

  return ok;

}



ll gcd(ll p, ll q) { return (q == 0) ? p : gcd(q, p % q); }

ll lcm(ll p, ll q) { return p / gcd(q, p) * q; }



// MOD

ll pow(ll a, ll n, ll m) {

  if (n == 0)

    return 1;

  if (n & 1)

    return ((a % m) * pow(a, n - 1, m)) % m;

  auto b = pow(a, n / 2, m);

  return (b * b) % m;

}

ll inv(ll a, ll p) { return pow(a, p - 2, p); }



template <ll N, ll M> struct Factrial {

  Factrial() {

    fact[0] = 1;

    for (int i = 1; i <= N; ++i)

      fact[i] = (fact[i - 1] * i) % M;

    finv[N] = inv(fact[N], M);

    for (int i = N; i > 0; --i)

      finv[i - 1] = (finv[i] * i) % M;

  }

  array<ll, N + 1> fact;

  array<ll, N + 1> finv;

  ll comb(ll n, ll m) const {

    if (m < 0 || n < m)

      return 0LL;

    return (fact[n] * ((finv[m] * finv[n - m]) % M)) % M;

  }

};



constexpr ll MOD = 1e9 + 7;



int main() {

  ll N;

  input(N);

  auto X = vec<double>(N);

  auto Y = vec<double>(N);

  for (auto &&i : range(N)) {

    input(X[i], Y[i]);

  }

  dump(N, X, Y);

  auto dist2 = [](double x0, double y0, double x1, double y1) {

    return (x0 - x1) * (x0 - x1) + (y0 - y1) * (y0 - y1);

  };

  auto lerp = [](double x0, double x1, double t) {

    return (1 - t) * x0 + t * x1;

  };

  double px = 0;

  double py = 0;

  double move = 2000;

  for (auto &&ig0 : range(100)) {

    for (auto &&ig1 : range(100)) {

      double maxD = dist2(X[0], Y[0], px, py);

      ll maxI = 0;

      for (auto &&i : range(1, N)) {

        double d = dist2(X[i], Y[i], px, py);

        if (d > maxD) {

          maxI = i;

          maxD = d;

        }

      }

      double d = sqrt(maxD);

      px = px + move * (X[maxI] - px) / d;

      py = py + move * (Y[maxI] - py) / d;

    }

    move *= 0.5;

  }

  auto computeRadius = [&X, &Y, &dist2](double cx, double cy) {

    double maxD = dist2(X[0], Y[0], cx, cy);

    for (auto &&i : range(1, X.size())) {

      double d = dist2(X[i], Y[i], cx, cy);

      maxD = max(maxD, d);

    }

    return (double)sqrtl(maxD);

  };



  printf("%.10lf\n", computeRadius(px, py));

}


// Faster C++ solution for the same problem (measured speedup: 1.3953920473402581x):
//#pragma GCC optimize("O3")

//#pragma GCC target("avx")



#include <algorithm>

#include <cmath>

#include <functional>

#include <iomanip>

#include <iostream>

#include <iterator>

#include <list>

#include <map>

#include <numeric>

#include <queue>

#include <random>

#include <set>

#include <sstream>

#include <string>

#include <type_traits>

#include <unordered_map>

#include <unordered_set>

#include <utility>

#include <vector>



using namespace std;



// Types

using ll = long long int;

using str = string;

template <class T> using u_set = unordered_set<T>;

template <class K, class V> using u_map = unordered_map<K, V>;

template <class V> using graph = u_map<V, u_set<V>>;

template <class F,

          typename enable_if<is_function<F>::value, nullptr_t>::type = nullptr>

using fun = function<F>;



namespace io {

// Input

using IS = istream;

IS &in(IS &);

IS &in(IS &i) { return i; }

template <class T, class... Ts> IS &in(IS &i, T &a, Ts &... as) {

  return in(i >> a, as...);

}

template <class V> IS &operator>>(IS &i, vector<V> &a) {

  for_each(a.begin(), a.end(), [&i](auto &e) { i >> e; });

  return i;

}

template <class F, class S> IS &operator>>(IS &i, pair<F, S> &p) {

  return in(i, p.first, p.second);

}

template <class... Ts, size_t... I>

IS &tuple_in(IS &i, tuple<Ts...> &t, index_sequence<I...>) {

  return in(i, get<I>(t)...);

}

template <class... Ts> IS &operator>>(IS &i, tuple<Ts...> &t) {

  return tuple_in(i, t, make_index_sequence<sizeof...(Ts)>());

}

// Output

using OS = ostream;

OS &out(OS &o) { return o << endl; }

template <class T> OS &out(OS &o, T const &a) { return o << a << endl; }

template <class T, class... Ts> OS &out(OS &o, T const &a, Ts const &... as) {

  return out(o << a << " ", as...);

}

template <class F, class S> OS &operator<<(OS &o, pair<F, S> const &p) {

  return o << p.first << ":" << p.second;

}

template <class... Ts> OS &args_out(OS &o, Ts const &... ts);

OS &args_out(OS &o) { return o; }

template <class T> OS &args_out(OS &o, T const &t) { return o << t; }

template <class T0, class T1, class... Ts>

OS &args_out(OS &o, T0 const &t0, T1 const &t1, Ts const &... ts) {

  return args_out(o << t0 << ",", t1, ts...);

}

template <class... Ts, size_t... I>

OS &tuple_out(OS &o, tuple<Ts...> const &t, index_sequence<I...>) {

  return args_out(o, get<I>(t)...);

}

template <class... Ts> OS &operator<<(OS &o, tuple<Ts...> const &t) {

  return tuple_out(o << "(", t, make_index_sequence<sizeof...(Ts)>()) << ")";

}

template <

    class C,

    class T = typename iterator_traits<typename C::iterator>::value_type,

    typename enable_if<!is_same<C, str>::value, nullptr_t>::type = nullptr>

OS &operator<<(OS &o, C const &a) {

  return a.empty() ? (o << "[]") : ([&o, &a]() -> OS & {

    o << "[" << *a.begin();

    for_each(next(a.begin()), a.end(), [&o](auto const &e) { o << "," << e; });

    return o << "]";

  }());

}

} // namespace io

auto input = [](auto &... a) { io::in(cin, a...); };

auto print = [](auto const &... a) { io::out(cout, a...); };

#ifdef JUMPAKU_DEBUG

auto dump = [](auto const &... a) { io::out(cerr, a...); };

#else

auto dump = [](auto const &...) {};

#endif



// Hash

namespace hashcode {

template <class... Ts> size_t hash_args(size_t h, Ts const &... ts);

size_t hash_args(size_t h) { return h; }

template <class T, class... Ts>

size_t hash_args(size_t h, T const &t, Ts const &... ts) {

  return hash_args(((h << 10) - h + hash<T>{}(t)), ts...);

}

template <class... Ts, size_t... I>

size_t hash_tuple(tuple<Ts...> const &t, index_sequence<I...>) {

  return hash_args(17, get<I>(t)...);

}

} // namespace hashcode

namespace std {

template <class... Ts> struct hash<tuple<Ts...>> {

  size_t operator()(tuple<Ts...> const &t) const {

    return hashcode::hash_tuple(t, index_sequence_for<Ts...>());

  }

};

} // namespace std



// Range

vector<ll> range(ll const &begin, ll const &end) {

  vector<ll> ret(max(0LL, end - begin));

  iota(ret.begin(), ret.end(), begin);

  return ret;

}

vector<ll> range(ll const &end) { return range(0, end); }

template <class T = ll> vector<T> vec(size_t n, T &&init = T()) {

  return vector<T>(n, init);

}



ll bisect(ll ng, ll ok, fun<bool(ll)> const &is_ok) {

  while (ok - ng > 1) {

    dump(ng, ok);

    ll m = ng + (ok - ng) / 2;

    (is_ok(m) ? ok : ng) = m;

  }

  return ok;

}



ll gcd(ll p, ll q) { return (q == 0) ? p : gcd(q, p % q); }

ll lcm(ll p, ll q) { return p / gcd(q, p) * q; }



// MOD

ll pow(ll a, ll n, ll m) {

  if (n == 0)

    return 1;

  if (n & 1)

    return ((a % m) * pow(a, n - 1, m)) % m;

  auto b = pow(a, n / 2, m);

  return (b * b) % m;

}

ll inv(ll a, ll p) { return pow(a, p - 2, p); }



template <ll N, ll M> struct Factrial {

  Factrial() {

    fact[0] = 1;

    for (int i = 1; i <= N; ++i)

      fact[i] = (fact[i - 1] * i) % M;

    finv[N] = inv(fact[N], M);

    for (int i = N; i > 0; --i)

      finv[i - 1] = (finv[i] * i) % M;

  }

  array<ll, N + 1> fact;

  array<ll, N + 1> finv;

  ll comb(ll n, ll m) const {

    if (m < 0 || n < m)

      return 0LL;

    return (fact[n] * ((finv[m] * finv[n - m]) % M)) % M;

  }

};



constexpr ll MOD = 1e9 + 7;



int main() {

  ll N;

  input(N);

  double X[N];

  double Y[N];

  for (auto &&i : range(N)) {

    input(X[i], Y[i]);

  }

  // dump(N, X, Y);

  auto dist2 = [](double x0, double y0, double x1, double y1) {

    return (x0 - x1) * (x0 - x1) + (y0 - y1) * (y0 - y1);

  };

  double px = X[0];

  double py = Y[0];

  double move = 2048;

  while (move > 0.49e-6) {

    for (auto &&ig1 : range(50)) {

      double maxD = dist2(X[0], Y[0], px, py);

      ll maxI = 0;

      for (auto &&i : range(1, N)) {

        double d = dist2(X[i], Y[i], px, py);

        if (d > maxD) {

          maxI = i;

          maxD = d;

        }

      }

      double d = sqrt(maxD);

      double t = move / d;

      px = (1 - t) * px + t * X[maxI];

      py = (1 - t) * py + t * Y[maxI];

    }

    move *= 0.5;

  }

  auto computeRadius = [&](double cx, double cy) {

    double maxD = dist2(X[0], Y[0], cx, cy);

    for (auto &&i : range(1, N)) {

      double d = dist2(X[i], Y[i], cx, cy);

      maxD = max(maxD, d);

    }

    return (double)sqrtl(maxD);

  };



  printf("%.10lf\n", computeRadius(px, py));

}