#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;

int main(){
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	int k; cin >> k;
	double res=0.0;
	for(int i=1;i<=k;i++){
		res+=1.0/(double)i;
	}
	res/=(double)k;
	printf("%.9f\n",res);
}