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

/**************************************************************
	Problem: 1014
	User: chenjunlin
	Language: C++
	Result: Accepted
	Time:6 ms
	Memory:2072 kb
****************************************************************/