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

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