#include<iostream>

int main(){
	int k;
	double cnt = 0;
	std::cin >> k;
	if (k == 1) {
	    cnt = 1;
	}
	else {
	    for (int i = 1; i <= k; i++) {
		cnt = cnt + (1./i);
	    }
	}
	double ans;
	ans = cnt/k;
	std::cout << ans << "\n";
}