#define _USE_MATH_DEFINES
#include <cstdio>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <complex>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <limits>
#include <climits>
#include <cfloat>
#include <functional>
#include <iterator>
using namespace std;

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

    vector<double> dp(8, 0.0);
    dp[0] = 1.0;
    while(--n >= 0){
        vector<double> nextDp(8, 0.0);
        for(int i=0; i<=6; ++i){
            nextDp[i]   += dp[i] * i / 6.0;
            nextDp[i+1] += dp[i] * (6 - i) / 6.0;
        }
        dp.swap(nextDp);
    }
    printf("%.10f\n", dp[6]);

    return 0;
}