#include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) begin(v),end(v)
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }
using ll = long long;
using pii = pair<int, int>;
constexpr ll INF = 1ll<<30;
constexpr ll longINF = 1ll<<60;
constexpr ll MOD = 1000000007;
constexpr bool debug = false;
//---------------------------------//

int main() {
	int N;
	cin >> N;
	if (N >= 150) puts("0.9999999999");
	double dp[2][7] {};
	dp[0][0] = 1;
	REP(i, N) {
		const int cur = i & 1, nex = cur ^ 1;
		fill(dp[nex], dp[nex + 1], 0);
		REP(j, 7) {
			dp[nex][j] += dp[cur][j] * j / 6;
			if (j + 1 < 7) dp[nex][j + 1] += dp[cur][j] * (6 - j) / 6;
		}
	}
	printf("%.18f\n", dp[N & 1][6]);
}