#include <iostream>
#include <algorithm>
#include <vector>

using namespace std;

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

  vector<double> dp(7);
  dp[0] = 1;
  for (int i = 0; i < n; i++) {
    for (int j = 5; j >= 0; j--) {
      dp[j + 1] += dp[j] * (6 - j) / 6.0;
      dp[j] = dp[j] * j / 6.0;
    }
  }

  printf("%.20f\n", dp[6]);
}