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

/**************************************************************
	Problem: 1014
	User: wtq001
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/