I would approach it like this:
sizes = [100, 250] print "How much space should the random song list occupy?" print '\n'.join("{0}. {1}Mb".format(n, s) for n, s in enumerate(sizes, 1)) # present choices choice = int(raw_input("Enter choice:")) # throws error if not int size = sizes[0] # safe starting choice if choice in range(2, len(sizes) + 1): size = sizes[choice - 1] # note index offset from choice print "You want to create a random song list that is {0}Mb.".format(size) You could also loop until you get an acceptable answer and cover yourself in case of error:
choice = 0 while choice not in range(1, len(sizes) + 1): # loop try: # guard against error choice = int(raw_input(...)) except ValueError: # couldn't make an int print "Please enter a number" choice = 0 size = sizes[choice - 1] # now definitely valid