#include <iostream>
 
template<typename T, typename U>
auto helper(T a, U b, int) -> decltype (a/b) {
	std::cout << "first" << std::endl;
	return a/b;
}
 
template<typename T, typename U>
auto helper(T a, U b, ...) -> decltype (a * (U(1)/b)) {
	std::cout << "second" << std::endl;
	return a * (U(1)/b);
}
 
template<typename T, typename U>
auto smart_division(T a, U b) -> decltype (helper(a, b)) {
    return helper(a, b, 0);
}
 
 
struct Test {
	explicit Test(int) {}
};
int operator / (Test a, Test b) {
return 1;
}
 
int main() {
	std::cout << smart_division(1.0, 2.0) << std::endl;
    Test t{5};
	std::cout << smart_division(1, t) << std::endl;
	return 0;
}

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