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

/**************************************************************
	Problem: 1014
	User: xuezihong1
	Language: C++
	Result: Accepted
	Time:14 ms
	Memory:2072 kb
****************************************************************/