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

/**************************************************************
	Problem: 1014
	User: fuhoubin
	Language: C++
	Result: Accepted
	Time:15 ms
	Memory:2072 kb
****************************************************************/