Write a function even_sum(a, b) that gets two integers a and b greater than zero and returns
the sum of the even integers n that are not multiple of b and 0 < n≤ a. For instance even_sum(10, 3)
is 2 + 4 + 8 + 10 = 24.
About statements
The official statement of a problem is always the one
in the PDF document. The HTML version of the statement
is also given to help you, but may contain some content
that is not well displayed. In case of doubt, always use the PDF.