Countries and Capitals

import random
b = -1
picked = []
countries=["Argentina", "Bolivia", "Brazil", "Chile", "Colombia", "Ecuador", "Guyana", "Paraguay", "Peru", "Surinam", "Uruguay", "Venezuela"]
capitals=["Buenos Aires", "Sucre", "Brasilia", "Santiago", "Bogota", "Quito", "Georgetown", "Asuncion", "Lima", "Paramaribo", "Montevideo", "Caracas"]
print("Let's play Guess the Capital!")
def getNumber():
	b = random.randrange(0,11)
def main():
	getNumber()
	while True:
		if b in picked:
			getNumber()
		else:
			break
	picked.append(b)
	print(countries[b])
	guess = input("Name the Capital:")
	if guess is capitals[b]:
		print("Correct!")
	else:
            print("Sorry, the answer was {0}.".format(capitals[b])
    while True:
        main()
        if input("Done?") is "yes":
            break
        elif len(b) >= 11:
            break