#include <cassert>
#include <cstddef>
#include <iostream>
#include <type_traits>

int choose(int) { return 1; }
int choose(int*) { return 2; }
bool is_empty(int* p) { return p == nullptr; }
template<class T>
bool relay(T value) { return is_empty(value); }

int main() {
    static_assert(std::is_same<decltype(nullptr), std::nullptr_t>::value, "null type");
    assert(choose(0) == 1);
    assert(choose(nullptr) == 2);
    assert(relay(nullptr));
    int n = 7;
    int* p = nullptr;
    assert(!p);
    p = &n;
    assert(*p == 7);
    std::cout << choose(nullptr) << ' ' << *p << '\n';
}