#include <cassert>
#include <cmath>
#include <algorithm>
#include <iostream>
#include <iomanip>
#include <limits.h>
#include <map>
#include <queue>
#include <set>
#include <string.h>
#include <vector>

using namespace std;
typedef long long ll;

int main() {
  int N;
  cin >> N;

  double dp[N + 1][7];
  memset(dp, 0, sizeof(dp));
  dp[0][0] = 1.0;

  for (int i = 0; i < N; ++i) {
    for (int j = 0; j <= 6; j++) {
      dp[i + 1][j + 1] += (6.0 - j) / 6.0 * dp[i][j];
      dp[i + 1][j] += (j / 6.0) * dp[i][j];
    }
  }

  cout << fixed << setprecision(10) << dp[N][6] << endl;

  return 0;
}