#include <iostream>
#include <exception>

template <class T>
T& cool_min(T& a, T& b) {
    return (a < b) ? a : b;
}


class InvalidIndexException : public std::exception {
public:
    explicit InvalidIndexException(int index) : index_(index) {}
    [[nodiscard]] int Index() const { return index_;}
    const char* what() {
        return "Invalid Index";
    }
private:
    int index_;
};


template <int N, class T>
class CArray {
public:
    CArray() : arr_(new T[N]), size_(N) {
    }
    [[nodiscard]] int Size() const { return size_;}
    T& operator[] (const int index) {
        if(index < 0 || index >= size_)
            throw InvalidIndexException(index);
        return arr_[index];
    }
private:
    T* arr_;
    int size_;
};


int main() {
    std::string s1 = "c", s2 = "b";
    cool_min(s1, s2);
    std::cout << cool_min(s1, s2) << "\n";

    CArray<5, int> arr;
    arr[4] = 3;
    std::cout << arr[4] << "\n";
    try {
        arr[8] = 123;
    }
    catch(InvalidIndexException &e) {
        std::cout << e.what() << "\n";
        std::cout << "Wrong index = " << e.Index() << "\n";
    }
    return 0;
}