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

int main(){
    int n;
    cin >> n;
    vector<double> dp(7);
    dp[6] = 1;
    for(int i = 0; i < n; i++){
        for(int i = 1; i <= 6; i++){
            dp[i - 1] += dp[i] * i / 6;
            dp[i] *= (double)(6 - i) / 6;
        }
    }
    printf("%.15lf\n", dp[0]);
}