#incudle <bits/stdc++.h>
using namespace std;
int main(){
	int n,i=1;
	float a=0;
	cin>>n;
	while(i<=n){
		a=a+1.0/i;
		i++;	
	}
	printf("%.3f",a);
}
/**************************************************************
	Problem: 1014
	User: panyuchen
	Language: C++
	Result: Compile Error
****************************************************************/