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

/**************************************************************
	Problem: 1014
	User: czr
	Language: C++
	Result: Accepted
	Time:16 ms
	Memory:2072 kb
****************************************************************/