#include <bits/stdc++.h>
using namespace std;
int main(){
  float s=0;
  int n;
  cin>>n;
  int i=1;
  while(i<=n){
    s=s+1.0/i;
    i++; 
  }
  printf("%.3f",s);
   
    return 0;
}
/**************************************************************
	Problem: 1014
	User: zhengyuxuan
	Language: C++
	Result: Accepted
	Time:10 ms
	Memory:2072 kb
****************************************************************/