#include <iostream>
#include <iomanip>
using namespace std;

int main(){
	int i,n;
	double s = 0;
	cin>>n;
	
	for(i = 1;i <= n;i++){
		s = s + 1.0 / i;
	} 
	cout<<fixed<<setprecision(3)<<s<<endl;
	
}

/**************************************************************
	Problem: 1014
	User: admin
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/