#include<bits/stdc++.h>
using namespace std;
int main(){
    int i,n;
    double s=0;
    cin>>n;
    for(i=1;i<=n;i++){
        s=s+1./i;
    } 
    printf("%.3f",s);
}
/**************************************************************
	Problem: 1014
	User: wuhanyu
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/