#include<bits/stdc++.h>
using namespace std;
int main(){
    int n;
    double y=0;
    cin>>n;
    for(int i=1;i<=n;i++){
        y += 1.0/i;
    }
    printf("%.3f",y);
}
/**************************************************************
	Problem: 1014
	User: lidongbo
	Language: C++
	Result: Accepted
	Time:6 ms
	Memory:2072 kb
****************************************************************/