#include <bits/stdc++.h>
using namespace std;
int main(){
	int i,n;
	double a;
	a=0;
	cin>>n;
	i=2;
	while(i<=n) {a=a+1/(i*1.0);i++;}
	a=a+1;
	printf("%.3f",a);
	return 0;
	}

/**************************************************************
	Problem: 1014
	User: ljl2
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/