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


/**************************************************************
	Problem: 1014
	User: cx001
	Language: C++
	Result: Accepted
	Time:10 ms
	Memory:2072 kb
****************************************************************/