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

/**************************************************************
	Problem: 1014
	User: wuzhijing
	Language: C++
	Result: Wrong Answer
****************************************************************/