C++ задача, хелпаните

 #include 

using namespace std;

class Alphabet { 
public: 
    Alphabet() { 
        initialize(); 
    } 
    char letter(const size_t index) const { 
        if (count <= index) return '?'; 
        return alphabet[index]; 
    } 
private: 
    static constexpr size_t count = 26; 
    char alphabet[count]; 
    void initialize() { 
        auto letter{ 'a' }; 
        for (size_t i = 0; i < count; ++i, ++letter) { 
            alphabet[i] = letter; 
        } 
    } 
};

int main() { 
    Alphabet alphabet; 
    size_t index; 
    while (true) { 
        cout << "index:  "; 
        cin >> index; 
        cout << "letter: " << alphabet.letter(index) << '\n'; 
    } 
}