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

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