using System;

​

​

public class Program

{

    public class RationalNumber

    {

        public RationalNumber(int numerator, int denominator)

        {

            Numerator = numerator;

            Denominator = denominator;

        }

        public int Numerator { get; set; }

        private int _denominator { get; set; }

        public int Denominator 

        { 

            get { return _denominator; }

            set

            {

                if (value == 0)

                {

                    throw new InvalidOperationException("Invalid denominator, denominator must be a non-zero");

                }

                _denominator = value;

            }

        }

        public float Value 

        {

            get { return (float)Numerator / Denominator; }

        }

        public static RationalNumber operator +(RationalNumber c1, RationalNumber c2)

        {

            var numerator = c1.Numerator * c2.Denominator + c2.Numerator * c1.Denominator;

            var denominator = c1.Denominator * c2.Denominator;

            return new RationalNumber(numerator, denominator);

        }

    }

    public static void Main()

    {

        var x = new RationalNumber(1, 5);

        var y = new RationalNumber(1, 5);

        var z = new RationalNumber(1, 5);

        var result = x + y + z;

        Console.WriteLine(result.Value);

    }

}