#include <iostream>
#include <cmath>

class Derivable {
        double val, deriv;

    public:
        Derivable(double _val, double _deriv) : val(_val), deriv(_deriv) {}
    Derivable(double c): val(c), deriv(0) {}
    static Derivable IndependendVariable(double x) { return Derivable(x,1); }

    double getValue() const {return val;}
    double getDerivative() const {return deriv;}

    friend Derivable operator+(const Derivable& f1, const Derivable& f2);
    friend Derivable operator-(const Derivable& f1, const Derivable& f2);
    friend Derivable operator*(const Derivable& f1, const Derivable& f2);
    friend Derivable operator/(const Derivable& f1, const Derivable& f2);
    friend Derivable cos(Derivable f);
};

Derivable operator+(const Derivable& f1, const Derivable& f2) {
    return Derivable(f1.val + f2.val, f1.deriv + f2.deriv);
}

Derivable operator-(const Derivable& f1, const Derivable& f2) {
    return Derivable(f1.val - f2.val, f1.deriv - f2.deriv);
}

Derivable operator*(const Derivable& f1, const Derivable& f2) {
    return Derivable(f1.val * f2.val, f1.deriv * f2.val + f1.val * f2.deriv);
}

Derivable operator/(const Derivable& f1, const Derivable& f2) {
    return Derivable(f1.val / f2.val, (f1.deriv * f2.val - f1.val * f2.deriv) / f2.val / f2.val);
}

Derivable cos(Derivable f) {
    return Derivable(cos(f.val), -sin(f.val)*f.deriv);
}

//--------------------------------------

Derivable f(double x, double a) {
    Derivable xd = Derivable::IndependendVariable(x);
    return a*xd*xd*xd - cos(xd/2);
}

int main() {
    static const double EPS = 1e-5;
    double x = 1;
    double a;
    std::cin >> a;
    while (1) {
        Derivable thisF = f(x, a);
        if (fabs(thisF.getValue()) < EPS) break;
        x = x - thisF.getValue() / thisF.getDerivative();
    std::cout << x << std::endl;
    }
    std::cout << x << std::endl;
}