I am relatively new to python and I cannot get this simple string comparison to work. No matter what I type into the terminal, even if I type 'a', I get "Invalid Input". If anybody can help me find what I am doing wrong that would be great. I have also tried to assign answer choices in variables (ans1 = 'a', ans1 = 'b') but it seems to behave the same. Thank you
while True:
    pref = (input('Choose a or b '))
    if (pref != 'a') or (pref !='b'):
        print('Invalid input')
        time.sleep(2)
        continue
    else:
        break
print('same')
