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

/**************************************************************
	Problem: 1014
	User: zouliangyin
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2072 kb
****************************************************************/