#include <iostream>
#include <iomanip>

int main() {
    int n;
    std::cin >> n;
    double sum = 0.0;
    for (int i = 1; i <= n; ++i) {
        sum += 1.0 / i;
    }
    std::cout << std::fixed << std::setprecision(3) << sum << std::endl;
    return 0;
}    
/**************************************************************
	Problem: 1014
	User: fuyijun
	Language: C++
	Result: Accepted
	Time:6 ms
	Memory:2072 kb
****************************************************************/