import re
palavra = 'NLS3XX'
while True:
palavraFinal = re.sub(r'[a-z](\d)x', r'\1', palavra, flags=re.I)
if palavraFinal == palavra:
break
palavra = palavraFinal
print(palavraFinal)
aW1wb3J0IHJlCiAKIApwYWxhdnJhID0gJ05MUzNYWCcKd2hpbGUgVHJ1ZToKICAgIHBhbGF2cmFGaW5hbCA9IHJlLnN1YihyJ1thLXpdKFxkKXgnLCByJ1wxJywgcGFsYXZyYSwgZmxhZ3M9cmUuSSkKICAgIGlmIHBhbGF2cmFGaW5hbCA9PSBwYWxhdnJhOgogICAgICAgIGJyZWFrCiAgICBwYWxhdnJhID0gcGFsYXZyYUZpbmFsCiAKcHJpbnQocGFsYXZyYUZpbmFsKQ==