class Complex(val real: Int ,val imaginary: Int) {
    def +(operand: Complex) : Complex = {
      new Complex( real + operand.real , imaginary + operand.imaginary)
    }
    def -(operand: Complex) : Complex = {
      new Complex( real - operand.real , imaginary - operand.imaginary)
    }
    def *(operand: Complex) : Complex = {
      new Complex(real * operand.real - imaginary * operand.imaginary, real * operand.imaginary + imaginary * operand.real)
    }
    override def toString(): String = {
      real + (if (imaginary < 0) "" else  "+") + imaginary + "i"
    }
  }