from machine import Pin
import time

MAX = 15
count = 0

in_btn = Pin(14, Pin.IN, Pin.PULL_UP)
out_btn = Pin(27, Pin.IN, Pin.PULL_UP)

green = Pin(2, Pin.OUT)
red = Pin(4, Pin.OUT)
yellow = Pin(5, Pin.OUT)
blue = Pin(18, Pin.OUT)

green.on()

while True:

    if in_btn.value() == 0:
        if count < MAX:
            count += 1
            print("Cars:", count)

            yellow.on()
            time.sleep(0.3)
            yellow.off()

            if count >= MAX:
                green.off()
                red.on()

        while in_btn.value() == 0:
            time.sleep(0.05)

    if out_btn.value() == 0:
        if count > 0:
            count -= 1
            print("Cars:", count)

            blue.on()
            time.sleep(0.2)
            blue.off()

            green.on()
            red.off()

        while out_btn.value() == 0:
            time.sleep(0.01)