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







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