using System;

public class Rational
{

    int numerator;
    int denomenator;

    private Rational(int n, int d)
    {
        if (n > 0 && d < 0)
        {
            d = -d;
            n = -n;
        }

        for (int i = 2; i < d; i++)
        {
            if (n % i == 0 && d % i == 0)
            {
                n /= i;
                d /= i;
            }
        }

        numerator = n;
        denomenator = d;
    }

    public static Rational operator +(Rational a, Rational b)
    {
        int numer = a.numerator * b.denomenator + b.numerator * a.denomenator;
        int denumer = a.denomenator * b.denomenator;
        return new Rational(numer, denumer);
    }

    public static Rational operator -(Rational a, Rational b)
    {
        int numer = a.numerator * b.denomenator - b.numerator * a.denomenator;
        int denumer = a.denomenator * b.denomenator;
        return new Rational(numer, denumer);
    }

    public static Rational operator *(Rational a, Rational b)
    {
        return new Rational(a.numerator * b.numerator, a.denomenator * b.denomenator);
    }

    public static Rational operator /(Rational a, Rational b)
    {
        return new Rational(a.numerator * b.denomenator, a.denomenator * b.numerator);
    }

    public static Rational Parse(string input)
    {
        string[] inputArr = input.Split('/');
        int a;
        int b = 1;
        if (int.TryParse(inputArr[0], out a))
        {
            if (inputArr.Length == 2)
            {
                if (!int.TryParse(inputArr[1], out b))
                {
                    throw new ArgumentException();
                }
            }
            return new Rational(a, b);
        }
        throw new ArgumentException();
    }

    public override string ToString()
    {
        if (numerator % denomenator == 0) return (numerator / denomenator).ToString();
        return numerator.ToString() + '/' + denomenator;
    }

}