loop goes on infinitely when i want it to stop in random color generator game

I am trying to make a simple script to output a random color and i want the user to choose how many random colors they want but it produces infinite colors. I have only started python and it would be very appreciated if someone could help me even though it is an indentation problem. Here is the code:

import random

g = 0
a = input("How many random colors would you like? ")
if not a.isdigit():
    print("Please enter a number next time")
    quit()
while True:
    lister = "Purple", "Green", "Blue", "Red", "Orange", "Lime", "Yellow", "White", "Black", "Maroon", "Aqua", "Pink", "Teal", "Grey", "Gold", "Silver", "Bronze", "Fuchsia", "Magenta", "Violet", "Beige", "Indigo"
    z = random.choice(lister)
    print("Your color is: " + str(z))
    g += 1
    if g == a:
        break
    else:
        continue