#include<bits/stdc++.h>
using namespace std;
double sum=1;
int main(){
	int n,i=2;
	cin>>n;
	while(i<=n){
		sum=sum+1.0/i; 
		i++;
	}
	cout<<fixed<<setprecision(3)<<sum;
	return 0;
}
/**************************************************************
	Problem: 1014
	User: zhangziang
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/