MaxWZ

#include <iostream>
#include <string>
#include <algorithm>
#include <Windows.h>

using namespace std;

class Lettercount {
private:
    string str;
public:
    Lettercount() {};
    Lettercount(string stroka) : str(stroka) {};
    int count() {
        int letter_count = 0;
        string str_cop(str);
        transform(str_cop.begin(), str_cop.end(), str_cop.begin(), ::toupper);
        for (int i = 0; i < str_cop.length(); i++) {
            if (isalpha(str_cop[i])) {
                letter_count++;
            }
            if ((int(str_cop[i]) >= 'А' && int(str_cop[i]) <= 'Я') || (int(str_cop[i]) == 'Ё'))
            {
                letter_count++;
            }
        }
        return letter_count;
    }
};

int main()
{
    setlocale(LC_ALL, "Russian");
    SetConsoleCP(1251);
    SetConsoleOutputCP(1251);
    string your_stroka;
    cout << "Enter the string: ";
    cin >> your_stroka;
    Lettercount obj(your_stroka);
    cout << "Your result: " << obj.count();
    return 0;
}