#include<bits/stdc++.h>
using namespace std;
int main(){
float s=0.0,n,b=1;
cin>>n;
while(b<=n){
s=s+(1/b);
b++;
}
printf("%.3f",s);
return 0;}

/**************************************************************
	Problem: 1014
	User: fzy001
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/