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

/////////////////// メイン ///////////////////

int main () {
  
  //////////////////// 入力 ////////////////////

  int n;
  cin >> n;

  //////////////// 出力変数定義 ////////////////

  double result = 0.0;

  //////////////////// 処理 ////////////////////

  vector<long long> vec = {4000000000LL, 3000000000LL, 2250000000LL, 1687500000, 1265625000, 949218750, 711914062, 533935547, 400451660, 300338745, 225254059, 168940544, 126705408, 95029056, 71271792, 53453844, 40090383, 30067787, 22550840, 16913130, 12684848, 9513636, 7135227, 5351420, 4013565, 3010174, 2257630, 1693223, 1269917, 952438, 714328, 535746, 401810, 301357, 226018, 169513, 127135, 95351, 71513, 53635, 40226, 30170, 22627, 16970, 12728, 9546, 7159, 5370, 4027, 3020, 2265, 1699, 1274, 956, 717, 538, 403, 302, 227, 170, 128, 96, 72, 54, 40, 30, 23, 17, 13, 10, 7, 5, 4, 3, 2, 2, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
  result = vec.at(n)/1e9;

  //////////////////// 出力 ////////////////////

  cout << fixed << setprecision(9) << result << endl;

  //////////////////// 終了 ////////////////////

  return 0;

}