#include <iostream>
template<typename T, typename F>
T use_f(T v, F f)
{
    static int count = 0;
    count++;
    std::cout << " use_f count = " << count << ", &count = " << &count << std::endl;
    return f(v);
}

class Fp
{
private:
    double z_;
public:
    Fp(double z = 1.0) : z_(z){}
    double operator()(double p) { return z_ * p; }
};

class Fq
{
private:
    double z_;
public:
    Fq(double z = 1.0) : z_(z){}
    double operator()(double q) { return z_ + q; }
};