#include <iostream>
#include <fstream>
#include <sstream>
#include <iomanip>
#include <vector>
#include <string>
#include <algorithm>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <unordered_set>
#include <unordered_map>
#include <bitset>
#include <limits>
#include <random>
#include <complex>
#include <cmath>
#include <cstdio>
#include <cstdlib>
using namespace std;
typedef long long ll;

#define REP(i,n) for(int (i)=0;(i)<(int)(n);(i)++)
#define RREP(i,n) for(int (i)=(int)(n)-1;i>=0;i--)
#define REMOVE(Itr,n) (Itr).erase(remove((Itr).begin(),(Itr).end(),n),(Itr).end())

double dp[1000010][8];

void dfs(vector<int> num) {
    if (num.size() == 6) {
        int s[6] = {};
        int cnt = 0;
        REP(i,num.size()) {
            if (s[num[i]] == 0) {
                s[num[i]]++;
                cnt++;
            }
        }
        dp[6][cnt] += 1.0 / pow(6.0, 6.0);
        return;
    }
    REP(i,6) {
        vector<int> num_t = num;
        num_t.push_back(i);
        dfs(num_t);
    }
}

int main() {

    int N; cin >> N;
    if (N <= 5) {
        cout << 0 << endl;
        return 0;
    }

    dfs({});

    for (int i = 7; i <= N; i++) {
        for (int j = 1; j <= 6; j++) {
            dp[i][j] += dp[i - 1][j] * (double) j / 6.0;
            dp[i][j + 1] += dp[i - 1][j] * (double) (6 - j) / 6.0;
        }
    }

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

    return 0;
}