#include <iostream>

using namespace std;

int NOD(int a, int b) {
    if (a < b) {
        swap(a, b);
    }
    while (a % b != 0) {
        a = a % b;
        swap(a, b);
    }
    return b;
}

int nok(int a, int b)
{
    int max = b;
    for (int i = max; i > 0; i++) {

        if ((i % a == 0) && (i % b == 0)) {
            return i;
        }
    }
}

class Rational {
public:
    Rational(){
        p = 0;
        q = 1;
    }
    Rational(int numerator, int denominator):p(numerator), q(denominator){
        if ((p < 0 && q < 0) || q < 0) {
            p *= -1;
            q *= -1;
        }
        if (p == 0) {
            q = 1;
        }
        else {
            int t = NOD(p, q);
            if (t != 1) {
                p /= t;
                q /= t;
            }
        }
    }

    int Numerator() const {
        return p;
    }
    int Denominator() const {
        return q;
    }
    bool operator == (Rational& b) {
        return (Denominator() == b.Denominator() && Numerator() == b.Numerator());
    }

    Rational operator + (Rational& b) {

        int t = nok(Denominator(), b.Denominator());
        int q = t;
        int p = t / Denominator() * Numerator() + t / b.Denominator() * b.Numerator();
        Rational R(p, q);
        return R;
    }


    Rational operator - (Rational& b) {

        int t = nok(Denominator(), b.Denominator());
        int q = t;
        int p = t / Denominator() * Numerator() - t / b.Denominator() * b.Numerator();
        Rational R(p, q);
        return R;
    }
private:
    int p;
    int q;
};



int main() {
    {
        Rational r1(4, 6);
        Rational r2(2, 3);
        bool equal = r1 == r2;
        if (!equal) {
            cout << "4/6 != 2/3" << endl;
            return 1;
        }
    }

    {
        Rational a(2, 3);
        Rational b(4, 3);
        Rational c = a + b;
        bool equal = c == Rational(2, 1);
        if (!equal) {
            cout << "2/3 + 4/3 != 2" << endl;
            return 2;
        }
    }

    {
        Rational a(5, 7);
        Rational b(2, 9);
        Rational c = a - b;
        bool equal = c == Rational(31, 63);
        if (!equal) {
            cout << "5/7 - 2/9 != 31/63" << endl;
            return 3;
        }
    }

    cout << "OK" << endl;
    return 0;
}