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





/**************************************************************
	Problem: 1014
	User: 078899
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/