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

	return 0;
}
/**************************************************************
	Problem: 1014
	User: cyp
	Language: C++
	Result: Wrong Answer
****************************************************************/