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

const int MAXN = int(1e6);

int N;

double dp[MAXN + 1][6 + 1];

int main() {
  ios::sync_with_stdio(false);
  cin >> N;
  dp[1][1] = 1.0;
  for (int i = 1; i < N; ++i) {
    for (int j = 1; j <= 6; ++j) {
      if (j == 6) dp[i + 1][j] += dp[i][j];
      else {
        dp[i + 1][j] += dp[i][j] * j / 6;
        dp[i + 1][j + 1] += dp[i][j] * (6 - j) / 6;
      }
    }
  }
  cout << fixed << setprecision(9) << dp[N][6] << endl;
  return 0;
}