#include #define LLI long long int #define FOR(v, a, b) for(LLI v = (a); v < (b); ++v) #define FORE(v, a, b) for(LLI v = (a); v <= (b); ++v) #define REP(v, n) FOR(v, 0, n) #define REPE(v, n) FORE(v, 0, n) #define REV(v, a, b) for(LLI v = (a); v >= (b); --v) #define ALL(x) (x).begin(), (x).end() #define RALL(x) (x).rbegin(), (x).rend() #define ITR(it, c) for(auto it = (c).begin(); it != (c).end(); ++it) #define RITR(it, c) for(auto it = (c).rbegin(); it != (c).rend(); ++it) #define EXIST(c,x) ((c).find(x) != (c).end()) #define fst first #define snd second #define popcount __builtin_popcount #define UNIQ(v) (v).erase(unique(ALL(v)), (v).end()) #define bit(i) (1LL<<(i)) #ifdef DEBUG #include #else #define dump(...) ((void)0) #endif #define gcd __gcd using namespace std; template constexpr T lcm(T m, T n){return m/gcd(m,n)*n;} template void join(ostream &ost, I s, I t, string d=" "){for(auto i=s; i!=t; ++i){if(i!=s)ost< istream& operator>>(istream &is, vector &v){for(auto &a : v) is >> a; return is;} template istream& operator>>(istream &is, pair &p){is >> p.first >> p.second; return is;} template bool chmin(T &a, const U &b){return (a>b ? a=b, true : false);} template bool chmax(T &a, const U &b){return (a void fill_array(T (&a)[N], const U &v){fill((U*)a, (U*)(a+N), v);} int main(){ cin.tie(0); ios::sync_with_stdio(false); int K; while(cin >> K){ vector p(K+6); REP(_,5000){ REP(i,K){ double temp = 1.0; FORE(j,1,6){ if(i+j > K) temp += p[0] / 6; else temp += p[i+j] / 6; } p[i] = temp; } } cout << fixed << setprecision(12) << p[0] << endl; } return 0; }