import random
import time

random_list = []

for i in range(10, 21):
    random_list.append(i)

counter = 0

while True:
    counter += 1
    random_sec = random.choice(random_list)
    counter_sec = random_sec

    tic = time.perf_counter()

    while True:
        toc = time.perf_counter()
        if toc - tic > 1:
            counter_sec -= 1
            print(counter_sec)
            tic = toc
            if counter_sec <= 0:
                print("Bang!")
                break
    if counter > 5:
        break