Part 1: Design and realize a Java class ComplexNumber to represent complex numbers. The functionalities of interest for complex numbers are the following:

• creation of a complex number starting from two real numbers representing respectively the real and the imaginary parts.
• real: returns the real part of the complex number.
• imaginary: returns the imaginary part of the complex number.
• module: returns the module of the complex number.
• phase: returns the phase of the complex number.
• equalTo: verifies whether two complex numbers are equal.
• sum: returns the sum of two complex numbers.
• difference returns the difference of two complex numbers.
• product: returns the product of two complex numbers.
• quotient returns the quotient of two complex numbers.

Add to the class also a method that does overriding of toString inherited from Object in such a way that it returns a string representing in a suitable way a complex number.

Part 2: Write a public static method external to the class ComplexNumber that, taken a complex number as parameter, returns an integer between 0 and 4 representing the quadrant in which the complex number falls. The result should be 0 in case the complex number lies on one of the two axes.