#include <bits/stdc++.h>
using namespace std;
double PI = acos(-1.0);
long long mod = 1e9 + 7;
const long long inf = 92233720368547758;
long long T = 1;
vector<vector<long long> > v;
long long n, m, x, y, k;
vector<long long> dp, vis, depth;
string s;
long long ceil_(long long x, long long y) {
  if (x % y == 0) return x / y;
  return (x / y) + 1;
}
long long floor_(long long x, long long y) { return x / y; }
bool isPrime(long long n) {
  if (n <= 1) return false;
  if (n <= 3) return true;
  if (n % 2 == 0 || n % 3 == 0) return false;
  for (long long i = 5; i * i <= n; i = i + 6)
    if (n % i == 0 || n % (i + 2) == 0) return false;
  return true;
}
long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }
long long fpow(long long a, long long b) {
  return b ? fpow(a * a % mod, b / 2) * (b % 2 ? a : 1) % mod : 1;
}
long long power(float x, int y) {
  float temp;
  if (y == 0) return 1;
  temp = power(x, y / 2);
  if (y % 2 == 0)
    return temp * temp;
  else {
    if (y > 0)
      return x * temp * temp;
    else
      return (temp * temp) / x;
  }
}
string lower(string s) {
  for (int i = 0; i < s.length(); i++) s[i] = tolower(s[i]);
  return s;
}
long long inv(long long i) {
  if (i == 1) return 1;
  return (mod - (mod / i) * inv(mod % i) % mod) % mod;
}
void show_tree() {
  for (int i = 1; i <= n; i++) {
    for (int j = 0; j < v[i].size(); j++) cout << v[i][j] << " ";
    cout << "\n";
  }
}
void dfs(int i) {
  vis[i] = 1;
  for (auto u : v[i]) {
    if (!vis[u]) dfs(u);
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  cin >> T;
  while (T--) {
    cin >> n;
    cout << fixed << setprecision(7) << cos(PI / (4 * n)) / sin(PI / (2 * n))
         << "\n";
  }
  return 0;
}
