#include <bits/stdc++.h>
using namespace std;
int main(){
	int a;
	float l,k=1;
	cin>>a;
	for(l=2;l<=a;l++){
		k=k-1/l;
	}printf("%.4f",k);
}

/**************************************************************
	Problem: 1521
	User: tonghuawei
	Language: C++
	Result: Wrong Answer
****************************************************************/