#include<bits/stdc++.h>
using namespace std;
double sum=1;
int main(){
    int n,i=2;
    cin>>n;
    while(i<=n){
        sum=sum+1.0/i; 
        i++;
    }
    cout<<fixed<<setprecision(3)<<sum;
    return 0;
}
/**************************************************************
	Problem: 1014
	User: wuweimo
	Language: C++
	Result: Accepted
	Time:12 ms
	Memory:2072 kb
****************************************************************/