using System;
namespace P5_19
{
    public class ComplexNumber
    {
        private int real;
        private int imaginary;
        public ComplexNumber() : this(0, 0) 
        {
        }
        public ComplexNumber(int r, int i) 
        {
            real = r;
            imaginary = i;
        }
        public override string ToString()
        {
            return (System.String.Format("{0} + {1}i", real, imaginary));
        }
        public static ComplexNumber operator +(ComplexNumber a, ComplexNumber b)
        {
            return new ComplexNumber(a.real + b.real, a.imaginary + b.imaginary);
        }
        public static ComplexNumber operator -(ComplexNumber a, ComplexNumber b)
        {
            return new ComplexNumber(a.real - b.real, a.imaginary - b.imaginary);
        }
    }
    class Program
    {
        static void Main()
        {
            ComplexNumber a = new ComplexNumber(10, 12);
            ComplexNumber b = new ComplexNumber(8, 9);
            System.Console.WriteLine("Complex Number a = {0}", a.ToString());
            System.Console.WriteLine("Complex Number b = {0}", b.ToString());
            ComplexNumber sum = a + b;
            System.Console.WriteLine("Complex Number sum = {0}", sum.ToString());
            ComplexNumber difference = a - b;
            System.Console.WriteLine("Complex Number difference = {0}", difference.ToString());
            Console.ReadLine();
        } 
     }
}
