#include <bits/stdc++.h>
#define REP(i, a, n) for(ll i = ((ll) a); i < ((ll) n); i++)
using namespace std;
typedef long long ll;

ll N;

int main(void) {
  cin >> N;

  if(N < 6) {
    cout << 0 << endl;
    return 0;
  }

  double power[6];
  REP(i, 1, 6) power[i] = 1;
  REP(i, 1, 6) REP(j, 0, N) power[i] *= i;

  double p = 0;
  p += power[1] * 6;
  p -= power[2] * 15;
  p += power[3] * 20;
  p -= power[4] * 15;
  p += power[5] * 6;
  REP(i, 0, N) p /= 6;

  printf("%0.15lf\n", (1 - p));
}