#include<bits/stdc++.h>
using namespace std;
int main()
{ int n;
 cin>>n;
 float sun=0;
 int i=1;
 while(i<=n){
 	sun+=(1.0/i);
 	i++;
 }
 
 printf("%.3f",sun);
    return 0;
}

/**************************************************************
	Problem: 1014
	User: ct001
	Language: C++
	Result: Accepted
	Time:18 ms
	Memory:2072 kb
****************************************************************/