#include <bits/stdc++.h> #define MOD 1000000007 #define pe(str) return cout<<(str)<<endl,0 #define px(str) cout<<(str)<<endl,exit(0) #define accu(ac,v) cout<<setprecision(ac)<<v<<endl #define pr(str) cout<<(str)<<endl #define prpr(str) cout<<str<<endl #define db(str) cerr<<"debug:"<<(str)<<endl #define dbdb(str) cerr<<"debugs:"<<str<<endl #define re(i,n) for(int i=0;i<(n);i++) #define rre(i,n) for(int i=(n);i>=0;i--) #define rep(i,a,b) for(int i=(a);i<(b);i++) #define rrep(i,a,b) for(int i=(b);i>=(a);i--) #define bw(a,b,c) (((a)<=(b))&&((b)<=(c))) #define spre(a) setprecision(a) #define all(a) a.begin(),a.end() #define rall(a) a.rbegin(),a.rend() using namespace std; typedef long long ll; typedef unsigned long long ull; typedef long double ld; typedef pair<int,int> pii; typedef complex<int> point; template<class InputIterator> void dump(InputIterator first,InputIterator last,char delim=' '){ for(InputIterator it=first;it!=last;it++){ if(it!=first)cout<<delim; cout<<*it; } } ull p(ull x,ull y){ if(y==0) return 1; ull A=p(x,y/2)%MOD; return (y&1?((A*A)%MOD*x)%MOD: (A*A)%MOD); // return (y&1?((A*A)*x):(A*A)); } template<class T> void swp(T &a,T &b){ T t=a; a=b; b=t; } // No65 int main(void){ int k; cin>>k; double v[1000]; double *a=v+6; re(i,6)v[i]=0.0; rep(i,1,k+1){ a[i]=(a[i-1]+a[i-2]+a[i-3]+a[i-4]+a[i-5]+a[i-6])/6.0+1.0; } printf("%.12lf\n",a[k]); return 0; }