#include<bits/stdc++.h>
using namespace std;
int main(){
	int a;
	double s=0;
	cin>>a;
	for(int i=1;i<=a;i++)
	    s+=(double)(1*1.0/i);
	cout<<fixed<<setprecision(3)<<s<<endl;
}
/**************************************************************
	Problem: 1014
	User: linmiaoling
	Language: C++
	Result: Accepted
	Time:10 ms
	Memory:2072 kb
****************************************************************/