The easiest way to do this for an arbitrary length list would probably be something like:
from operator import itemgetter
from string import ascii_uppercase
data = [19, 14, 36]
labelled = zip(data, ascii_uppercase) # [(19, 'A'), (14, 'B'), (36, 'C')]
sorted_data = sorted(labelled,
key=itemgetter(0)) # [(14, 'B'), (19, 'A'), (36, 'C')]
labels = [pair[1] for pair in sorted_data] # ['B', 'A', 'C']