#include <bits/stdc++.h>
using namespace std;
int main(){
    double n,sum=0;
    cin>>n;
    for(double i=1;i<=n;i++)sum=sum+1/i;
    printf("%.3f",sum);
    return 0;
}
/**************************************************************
	Problem: 1014
	User: wengzihang
	Language: C++
	Result: Accepted
	Time:10 ms
	Memory:2072 kb
****************************************************************/