#include<bits/stdc++.h>
using namespace std;
using uint = unsigned int;
using ll = long long;
using ull = unsigned long long;
template<class T> using V = vector<T>;
template<class T> using VV = V<V<T>>;
template<class T> using VVV = V<VV<T>>;
template<class T> using VVVV = VV<VV<T>>;
#define rep(i,n) for(ll i=0ll;i<n;i++)
#define REP(i,a,n) for(ll i=a;i<n;i++)
const long long INF = (1LL << 60);
const long long mod99 = 998244353;
const long long mod107 = 1000000007;
const long long mod = mod99;
#define eb emplace_back
#define pb eb
#define be(v) (v).begin(),(v).end()
#define all(i,v) for(auto& i : v)
#define all2(i,j,v) for(auto& [i,j] : v)
template<class T, class U> void chmin(T& t, const U& u) { if (t > u) t = u; }
template<class T, class U> void chmax(T& t, const U& u) { if (t < u) t = u; }

// cin.tie(nullptr);
// ios::sync_with_stdio(false);
// cout << fixed << setprecision(20);

void solve(){
  ll k;
  cin >> k;
  V<double> v(k+100, 0.0);
  REP(i,1,k+6){
  	v[i] += 1.0;
  	REP(j, max(i-6, 0ll), min(k, i)) v[i] += v[j]/6;
  }
  cout << fixed << setprecision(20);
  double ans = 0.0;
  REP(i,k,k+100) ans += v[k];
  cout << ans << endl;
}





int main(){
  cin.tie(nullptr);
  ios::sync_with_stdio(false);
  int t=1;
  // cin >> t;
  rep(i,t) solve();
}