#include<bits/stdc++.h>
using namespace std;
int main(){
	int n;
	float s;
    cin>>n;
    s=0.0;
	for(int i=1;i<=n;i++){
		s+=1.0/i;
	}
	printf("%.3f",s);
    return 0;
}
/**************************************************************
	Problem: 1014
	User: xiaojingxuan
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/