#include <bits/stdc++.h>

using namespace std;

const int MAX = 1e6 + 10;
long double dp[8], dp2[8];
long double *now, *nxt;

int main() {
    int n;
    cin >> n;
    now = dp;
    nxt = dp2;
    now[0] = 1;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j <= 6; j++) {
            nxt[j] = 0;
        }
        for (int j = 0; j <= 6; j++) {
            long double hoge = now[j] / 6;
            nxt[j + 1] += hoge * (6 - j);
            nxt[j] += hoge * j;
        }
        swap(now, nxt);
    }
    cout << fixed << setprecision(10) << now[6] << endl;
    return 0;
}