import java.io.*;

 

public class Calculator

{  
     public static void main(String[] args)

   {  

      BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
      Complex num1, num2, result = new Complex();
      char op;
      boolean more;

 

      System.out.println("\nComplex number calculation program\n");

      do

      {  num1 = readComplex(in);

         num2 = readComplex(in);

 

         op = readChar(in, "Enter the operation '+, -, *, or /': ", "+-*/");

         switch (op)

         {  case '+':  result = num1.add(num2);

                       break;

            case '*':  result = num1.multiply(num2);

                       break;

            case '/':  result = num1.divide(num2);

                       break;

            case '-':  result = num1.subtract(num2);                   

         }

         System.out.println(num1+" "+op+" "+num2+" = "+result);

         more = (readChar(in, "Perform another calculation? (y/n): ", "yn") !='n');

                 

      } while (more);

           

      System.out.println("\n\nCalculation program completed\n");

   }

     

   // Method to read a complex number

   public static Complex readComplex(BufferedReader in)

   {  
   
            System.out.print("Enter a complex number: ");
            String comp = in.readLine();

   }

   // Method to read the first character of a string

   public static char readChar(BufferedReader in, String prompt, String chars)
   {   
           String pr = prompt;
           String ch = chars;
           pr = in.readLine();
           ch = in.readLine();

                                       
   }
}