#include<iostream> 
 
using namespace std;
 
int main()
{
    int n;
    cin>>n;
    float sum=0;
    int i=1;
    while(i<=n){
         
        sum+=1.0/i;
        i++;
    }
     
    printf("%.3f",sum);
     
     
}
/**************************************************************
	Problem: 1014
	User: wenda
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/