#include<bits/stdc++.h>
using namespace std;
int main(){
	float h=0;
	int a,b=1;
	cin>>a;
	while(b<=a){
		h=h+1.0/b;
		b++;
	}
	printf("%.3f",h);
} 
/**************************************************************
	Problem: 1014
	User: toughuatao1
	Language: C++
	Result: Accepted
	Time:14 ms
	Memory:2072 kb
****************************************************************/