#include <bits/stdc++.h>

using namespace std;

const int MAX = 1e6 + 10;
long double dp[MAX][7];

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