#include <bits/stdc++.h>
using namespace std;
int main() {
int n;
float h;
cin>>n;
for(int i=1;i<=n;i++){
	h=h+1.0/i ;       
	}
printf("%.3f",h);
}
 
/**************************************************************
	Problem: 1014
	User: chenxuanyi
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/