#include "bits/stdc++.h"
#define ALL(obj) (obj).begin(),(obj).end()
#define RALL(obj) (obj).rbegin(),(obj).rend()
#define REP(i, n) for(int i = 0; i < (int)(n); i++)
#define REPR(i, n) for(int i = (int)(n); i >= 0; i--)
#define FOR(i,n,m) for(int i = (int)(n); i < int(m); i++)
using namespace std;
typedef long long ll;
const int MOD = 1e9 + 7;
const int INF = MOD - 1;
const ll LLINF = 4e18;

int main() {
    int n; cin >> n;
    vector<vector<double>> dp(n + 1, vector<double>(7, 0));
    dp[0][0] = 1;
    FOR(i, 1, n + 1) {
        REP(j, 7) {
            dp[i][j] = dp[i - 1][j] * (double)(j)/6;
            if (j > 0) {
                dp[i][j] += dp[i - 1][j - 1] * ((double)(7 - j) / 6);
            }
        }
    }
    printf("%.10f", dp[n][6]);
    getchar(); getchar();
}