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

/**************************************************************
	Problem: 1014
	User: zhuangsongyu
	Language: C++
	Result: Accepted
	Time:19 ms
	Memory:2072 kb
****************************************************************/