#include<bits/stdc++.h>
using namespace std;
int main(){
    int n;
    double s=0;
    cin>>n;
    for(int i=1;i<=n;i++){
        s += 1.0/i;
    }
    printf("%.3lf",s);
}
/**************************************************************
	Problem: 1014
	User: hongjiaming
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/