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

/**************************************************************
	Problem: 1014
	User: tangkaixuan
	Language: C++
	Result: Accepted
	Time:6 ms
	Memory:2072 kb
****************************************************************/