#include<bits/stdc++.h>
using namespace std;
int main(){
	int n,i=1;
    cin>>n;
    float s=0;
    while(i<=n){
    	s=s+1.0/i;
    	i++;
	}
	printf("%.3f",s);
}
/**************************************************************
	Problem: 1014
	User: fandaohan
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/