Define a class Complex to represent complex numbers. All complex numbers are of the form x + yi, where x and y are real numbers, real numbers being all those numbers which are positive, negative, or zero.

In general, the x part of a complex number x + yi is called the real part, while y is called the imaginary part.

To add or subtract two complex numbers, you just add or subtract the corresponding real and imaginary parts. For instance, the sum of 5 + 3i and 4 + 2i is 9 + 5i. And the result of 3 + 4i minus 1 + 2i is 2 + 2i.

Two complex numbers are equal if and only if the real parts are equal and the imaginary parts are equal. For example, 3 + 2i and 3 + 2i are equal, but 3 + 2i and 3 + 4i are not equal.