#include <bits/stdc++.h>
using namespace std;
int main(){
 	float h=0;
 	int a=1,n;
	cin>>n;
	while(a<=n){
		h=h+1.0/a;
		a++;
	}
	printf("%.3f",h);
}
/**************************************************************
	Problem: 1014
	User: zhangyilei
	Language: C++
	Result: Accepted
	Time:15 ms
	Memory:2072 kb
****************************************************************/