from machine import Pin
from time import sleep
led_pins = [4, 5, 13, 14, 16, 17, 18, 21]
leds = [Pin(pin, Pin.OUT) for pin in led_pins]
green_button = Pin(34, Pin.IN, Pin.PULL_DOWN)
red_button = Pin(35, Pin.IN, Pin.PULL_DOWN)
car_count = 0
max_count = 8
old_green = 0
old_red = 0
def update_leds(count):
    for i in range(8):
        leds[i].value(1 if i < count else 0)
while True:
    new_green = green_button.value()
    new_red = red_button.value()
    if new_green == 1 and old_green == 0:
        if car_count < max_count:
            car_count += 1
            update_leds(car_count)
    if new_red == 1 and old_red == 0:
        if car_count > 0:
            car_count -= 1
            update_leds(car_count)
    old_green = new_green
    old_red = new_red
    sleep(0.05)