#include <cstdio>
#include <cmath>
#include <algorithm>

namespace mirai {

constexpr int MAXN = 1005;
constexpr long double PI = 3.14159265358979323846;
long double a[MAXN];

int main(int argc, char** argv) {
//  std::freopen("ala.out", "r", stdin);
  int n;
  std::scanf("%d", &n);
  for (int i = 0; i < n; ++i) {
    std::scanf("%Lf", &a[i]);
    if (a[i] > a[0]) {
      std::swap(a[i], a[0]);
    }
  }
  long double rl = a[0] / 2, rr = 1e9;
  auto f1 = [=](long double radius) -> long double {
    long double theta = 0;
    for (int i = 0; i < n; ++i) {
      theta += 2 * std::asin(a[i] / (radius * 2));
    }
    return theta;
  };
  while (rr - rl >= 5e-8) {
    long double mid = (rl + rr) / 2;
//    std::printf("%.10Lf %.10Lf %.10Lf\n", rl, rr, f1(mid));
    if (f1(mid) > 2 * PI) {
      rl = mid;
    } else {
      rr = mid;
    }
  }
  long double ans1 = (rl + rr) / 2;
  if (std::abs(f1(ans1) - 2 * PI) <= 5e-7) {
    std::printf("%.10Lf\n", ans1);
    return 0;
  }
  rl = a[0] / 2;
  rr = 1e9;
  auto f2 = [=](long double radius) -> long double {
    long double theta = 2 * std::asin(a[0] / (radius * 2));
    for (int i = 1; i < n; ++i) {
      theta -= 2 * std::asin(a[i] / (radius * 2));
    }
    return theta;
  };
//  std::puts("---------------------------");
  int cnt = 0;
  while (rr - rl >= 5e-8) {
    ++cnt;
    if (cnt == 100) {
      break;
    }
    long double mid = (rl + rr) / 2;
//    std::printf("%.10Lf %.10Lf %.10Lf\n", rl, rr, f2(mid));
    if (f2(mid) < 0) {
      rr = mid;
    } else {
      rl = mid;
    }
  }
  std::printf("%.10Lf\n", (rl + rr) / 2);
  return 0;
}

}

int main(int argc, char** argv) {
  return mirai::main(argc, argv);
}