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

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