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#include <iostream>
    #include <limits>
    
    template<typename K>
    class foo {
    public:
        template<typename T>
        std::enable_if_t<std::is_signed<T>::value && !std::is_signed<K>::value> func(T const& t) 
        {
            if (t < 0 || static_cast<std::make_unsigned_t<T>>(t) > std::numeric_limits<K>::max()) {
                std::cout << "error\n";
                return;
            }
            
            func_impl(t);
        }
        
        template<typename T>
        std::enable_if_t<!std::is_signed<T>::value && std::is_signed<K>::value> func(T const& t) 
        {
            if (t > static_cast<std::make_unsigned_t<K>>(std::numeric_limits<K>::max())) {
                std::cout << "error\n";
                return;
            }
            
            func_impl(t);
        }
        
        template<typename T>
        std::enable_if_t<std::is_signed<T>::value == std::is_signed<K>::value> func(T const& k)
        {
            if (k < std::numeric_limits<K>::min() || k > std::numeric_limits<K>::max()) {
                std::cout << "error\n";
                return;
            }
            func_impl(k);
        }
        
    private:
        void func_impl(K const& k) 
        {
            std::cout << "normal\n";
        }
    };
    
    
    int main()
    {
        foo<char>().func(127);
        foo<char>().func(127u);
        foo<char>().func(-128);
        foo<char>().func(128);
        foo<char>().func(128u);
        foo<char>().func(-129);
        foo<unsigned>().func(-1);
        foo<int>().func(1u);
    }

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Compilation time: 0.43 sec, absolute running time: 0.14 sec, cpu time: 0 sec, memory peak: 4 Mb, absolute service time: 0.59 sec