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

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