检测到Python键，但未运行其他代码

Question

I want to make a program that when I press Q, It takes a screenshot and save it. It can detect the keypress but doesn't run the other codes.

a = input()
b = ''
import time
import pyautogui
import PIL
import keyboard # Using module keyboard
while True: # making a loop
    try: 
        if keyboard.is_pressed('q'): # if key 'q' is pressed
            print('Detected')
            a+=1
            im = pyautogui.screenshot()
            b = ''
            b = str(a)
            b+=".jpg"
            im.save(b)
            print('Success')
            time.sleep(1)
        else:
            pass
    except:
        b = ''

But the results just come like this:

Detected
Detected
Detected
Detected
Detected
Detected
Detected
Detected
Detected
Detected
Detected

It just prints a lot of 'Detected' and doesn't run anymore.