#include <iostream>
using namespace std;
 
template<typename T>   // primary template
struct is_int : std::false_type
{};
 
template<>  // explicit specialization for T = int
struct is_int<int> : std::true_type
{};
 
template <typename T>
constexpr bool is_int_v = is_int<T>::value;
 
int main() {
    std::cout << is_int_v<char> << std::endl;  // prints 0 (false)
    std::cout << is_int<int>::value << std::endl;   // prints 1 (true)
    return 0;
}

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