ООП лаб 7(2)

#include <iostream>
#include <string>

using namespace std;

class tractor {
private:
    string brand,
           fuel_type,
           engine_power;
    double price;
public:
    tractor() {
        brand = "ERROR";
        fuel_type = "ERROR";
        engine_power = -1;
        price = -1;
    }
    tractor(string _brand, string _fuel_type, double _engine_power, double _price) {
        brand = _brand;
        fuel_type = _fuel_type;
        engine_power = _engine_power;
        price = _price;
    }
    tractor(const tractor& t) {
        brand = t.brand;
        fuel_type = t.fuel_type;
        engine_power = t.engine_power;
        price = t.price;
    }
    void input() {
        cout << endl;
        cout << "Enter brand: ";
        getline(cin, brand);
        cout << "Enter type of fuel: ";
        cin >> fuel_type;
        cin.ignore(37578, '\n');
        cout << "Enter engine power(kW): ";
        cin >> engine_power;
        engine_power += "kW";
        cin.ignore(37578, '\n');
        cout << "Enter price($): ";
        cin >> price;
        cin.ignore(37578, '\n');
    }
    void print() {
        cout << endl;
        cout << "Brand: " << brand << endl;
        cout << "Type of fuel: " << fuel_type << endl;
        cout << "Engine power: " << engine_power << endl;
        cout << "Price: " << price << '$' << endl;
    }
    bool operator== (const tractor& t) {
        if (price == t.price)
            return 1;
        return 0;
    }
    bool operator!= (const tractor& t) {
        if (price != t.price)
            return 1;
        return 0;
    }
    bool operator> (const tractor& t) {
        if (price > t.price)
            return 1;
        return 0;
    }
    bool operator< (const tractor& t) {
        if (price < t.price)
            return 1;
        return 0;
    }
    tractor operator+ (const tractor& t) {
        tractor res;
        res.brand = brand + " & " + t.brand;
        res.fuel_type = fuel_type + " & " + t.fuel_type;
        res.engine_power = engine_power + " & " + t.engine_power;
        res.price = price + t.price;
        return res;
    }
};

int main() {
    tractor belarus;
    belarus.input();
    tractor MT;
    MT.input();

    cout << endl;
    cout << "operator== for belarus and MT returned " << (belarus == MT) << endl;
    cout << "operator!= for belarus and MT returned " << (belarus != MT) << endl;
    cout << "operator< for belarus and MT returned " << (belarus < MT) << endl;
    cout << "operator> for belarus and MT returned " << (belarus > MT) << endl;

    tractor MTandBelarus = MT + belarus;
    MTandBelarus.print();
    return 0;
}