#include <algorithm> #include <bitset> #include <cmath> #include <iomanip> #include <iostream> #include <map> #include <numeric> #include <set> #include <sstream> #include <stack> #include <queue> #include <unordered_map> #include <unordered_set> #include <vector> #define rep(i, n) for (int i = 0; i < n; ++i) #define reps(i, s, n) for (int i = s; i < n; i++) #define debug(s, param) std::cerr << s << param << std::endl; using namespace std; using ll = long long; using pi = pair<int, int>; using pl = pair<ll, ll>; const int INF = 1e9; const ll INFL = 1e18; const ll MOD = 1000000007; int main() { int k; cin >> k; vector<double> dp(k + 6); for (int i = k - 1; i >= 0; --i) { dp[i] = 1; reps (j, 1, 7) dp[i] += (dp[i+j] / 6); } cout << dp[0] << endl; return 0; }