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






	return 0;
}

/**************************************************************
	Problem: 1014
	User: zy002
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/