Насколько отличается количество элементов кратных трем в первой половине массива от количества элементов кратных пяти во второй

arr = [9, -15, 3, 6, -10, -5, 12, 18, -20, 15]
half = len(arr) // 2
first_half = arr[:half]
second_half = arr[half:]
count_div_3 = sum(1 for x in first_half if x > 0 and x % 3 == 0)
count_div_5 = sum(1 for x in second_half if x < 0 and x % 5 == 0)
difference = count_div_3 - count_div_5
print("Разница:", difference)

def foo(arr):
    s1=s2=0
    sz=len(arr)
    h=sz//2
    for i in range(sz):
        a=arr[i]
        if i < h:
            s1=s1+a if a>0 and a % 3 == 0 else 0
        else:
            s2=s2+a if a < 0 and a % 5 == 0 else 0  
    return s1-s2

def foo(data):
    result = 0
    mid = len(data) // 2
    for i, v in enumerate(data):
        if i < mid and v > 0 and v % 3 == 0:
            result += 1
        elif i >= mid and v < 0 and v % 5 == 0:
            result -= 1
    return result

from itertools import islice
 
def foo(data):
    s1 = sum(1 for i in islice(data, None, len(data) // 2) if i > 0 and i % 3 == 0)
    s2 = sum(1 for i in islice(data, len(data) // 2, None) if i < 0 and i % 5 == 0)
    return s1 - s2