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

using int64 = long long;
using uint64 = unsigned long long;

double prop[7];

int main()
{
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    int N;
    cin >> N;

    prop[1] = 1;
    for (int i = 0; i < N - 1; i++)
    {
        for (int num = 6; num >= 1; num--)
        {
            prop[num] = (num / 6.0) * prop[num];
            prop[num] += (1.0 - (num - 1) / 6.0) * prop[num - 1];
        }
    }

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

    return 0;
}