Algorithms in Python

In programming, it is important to understand and analyze algorithms written by other people. Given below is some algorithm implemented in Python:

def foo(numbers):
    counter1 = 0
    counter2 = 0

    for num in numbers:
        if num % 2 == 0:
            counter1 += num if num < 4 else -num
        else:
            counter2 += num if num < 5 else -num

    return counter1 * counter2

What is the output of this algorithm for the list [3, 4, 2, 1, 5, 7]? Try not to run the interpreter but identify the output only reading the code snippet. Print your answer in the field below.