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

int n;

long double solve();

int main() {
  cin >> n;
  cout << fixed << setprecision(10);
  cout << solve() << endl;
  return 0;
}

long double solve() {
  long double res = 0;
  for (int i = 1; i <= 6; ++i) {
    long double now = 1;
    for (int j = 0; j < n; ++j) now *= i / 6.0L;
    for (int j = 0; j < i; ++j) now *= (6.0L - j) / (j + 1.0L);
    if (i & 1)
      res -= now;
    else
      res += now;
  }
  return res;
}