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

/**************************************************************
	Problem: 1014
	User: LYY001
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/