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

/**************************************************************
	Problem: 1014
	User: dengyuanyan
	Language: C++
	Result: Accepted
	Time:11 ms
	Memory:2072 kb
****************************************************************/