Magic Coupon

def solve(coupons, products):
    coupons = list(map(int, coupons.split(',')))
    products = list(map(int, products.split(',')))
    coupons.sort()
    products.sort()
    total = 0
    i = 0
    while i < len(coupons) and i < len(products) and coupons[i] < 0 and products[i] < 0:
        total += coupons[i] * products[i]
        i += 1
    i = 1
    while i <= len(coupons) and i <= len(products) and coupons[-i] > 0 and products[-i] > 0:
        total += coupons[-i] * products[-i]
        i += 1
    print(total)