void task3() {

    std::string roman;
    int arabic = 0;

    std::cin >> roman;

    bool check = true;

    while (std::cin >> roman) {
        for (int i = 0; i < roman.length(); i++) {
            if (roman[i] == 'I' || roman[i] == 'V' || roman[i] == 'X' || roman[i] == 'L' ||
                roman[i] == 'C' || roman[i] == 'D' || roman[i] == 'M') {
                check = true;
            }
            else {
                std::cout << "Wrong input data." << std::endl;
                std::exit(0);
            }
        }
    }

    int current_value = 0;


    bool order = false;


    for (int i = 0; i < roman.length(); i++) {


        if (roman[i] == 'C' && roman[i+1] == 'M' || roman[i] == 'C' && roman[i+1] == 'M' || roman[i] == 'C' && roman[i+1] == 'M' || ) {
            order = false;
            break;
        }


        if (roman[i] == 'C' && roman[i+1] == 'M') {
            current_value += 900;
        }
        else if (roman[i] == 'C' && roman[i+1] == 'D') {
            current_value += 400;
        }
        else if (roman[i] == 'X' && roman[i+1] == 'C') {
            current_value += 90;
        }
        else if (roman[i] == 'X' && roman[i+1] == 'L') {
            current_value += 40;
        }
        else if (roman[i] == 'I' && roman[i+1] == 'X') {
            current_value += 9;
        }
        else if (roman[i] == 'I' && roman[i+1] == 'V') {
            current_value += 4;
        }
        else if(roman[i] == 'M') {
            current_value += 1000;
        }
        else if (roman[i] == 'D') {
            current_value += 500;
        }
        else if (roman[i] == 'C') {
            current_value += 100;
        }
        else if (roman[i] == 'L') {
            current_value += 50;
        }
        else if (roman[i] == 'X') {
            current_value += 10;
        }
        else if (roman[i] == 'V') {
            current_value += 5;
        }
        else if (roman[i] == 'I') {
            current_value += 1;
        }
    }

    arabic = current_value;

    if (/*order == false || */arabic < 1 || arabic > 3999) {
        std::cout << "Wrong input data." << std::endl;
    }
    else {
        std::cout << "Converted " << roman << "to " << arabic << std::endl;
    }
}