#include <iostream>
#include<iomanip>
using namespace  std;
void main()  
{
    double sum1=0,sum2=0, i=0,b=1;  int n ;
   
    cin>>n;
   
if(n%2==0)
      {
          while(i<n);
            {
                i=i+2;
            sum1=sum1+(1/i);
            }
      cout<<sum1+1<<endl;
     }   
 
     
else
     {
         while(b<n);
         {
          b=b+2;
         sum2=sum2+(1/b);
           }
      
      cout<<sum2+1<<endl;
    }
}