#include "bits/stdc++.h"
using namespace std;
#define rep(i,n) for(int (i)=0;(i)<(int)(n);++(i))
#define rer(i,l,u) for(int (i)=(int)(l);(i)<=(int)(u);++(i))
#define reu(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))
static const int INF = 0x3f3f3f3f; static const long long INFL = 0x3f3f3f3f3f3f3f3fLL;
typedef vector<int> vi; typedef pair<int, int> pii; typedef vector<pair<int, int> > vpii; typedef long long ll;
template<typename T, typename U> static void amin(T &x, U y) { if (y < x) x = y; }
template<typename T, typename U> static void amax(T &x, U y) { if (x < y) x = y; }

int main() {
	int N;
	while (~scanf("%d", &N)) {
		vector<array<double,7>> dp(N+1);
		dp[0][0] = 1;
		rep(i, N) rep(j,7) {
			double x = dp[i][j];
			if (x < 1e-99) continue;
			double p = j * 1. / 6;
			dp[i + 1][j] += x*p;
			if(j<6)dp[i + 1][j+1] += x*(1-p);
		}
		auto ans = dp[N][6];
		printf("%.10f\n", ans);
	}
	return 0;
}