#include <iostream>
#include <algorithm>
#include <cstdio>
#include <string>
#include <vector>
#include <numeric>

#define ll long long

using namespace std;

//E(x)=E(x+1)∗1/6+E(x+2)∗1/6+E(x+3)∗1/6+E(x+4)∗1/6+E(x+5)∗1/6+E(x+6)∗1/6+1
int main(){
  
   int k;
   cin>>k;
   double E[21];
   E[0]=0;
   E[1]=1;
   for(int i=2;i<=7;++i) E[i]=E[i-1]*((double)7/6);
   for(int i=8;i<=20;++i) E[i]=(double)(E[i-1]+E[i-2]+E[i-3]+E[i-4]+E[i-5]+E[i-6])/6+1;

   printf("%.5lf\n",E[k]);

   return 0;
}