Updated Cities/List example

'''
This Python 2 program will build a list of favorite
cities based on input from the user, then compare the
cities to my list of favorite cities and output the
similarities. It then offers to delete a city from
the list and show the results.

UPDATED: refactor using sets, index, ...
'''

# Initialize my list with my favorite cities
myCities = ['New York','Los Angeles','London','Paris']

# Print out my favorite cities
print "My favorite cities are: ",myCities
print ""

# Ask the user for the number of cities they want to enter
yourCityCount = raw_input ("How many favorite cities do you have?: ")

# Validate that the input is a positive number
while not(yourCityCount.isdigit()):
  yourCityCount = raw_input ("How many favorite cities do you have? (NUMBERS ONLY): ")

# Change type to integer
yourCityCount = int(yourCityCount)

# Setup an empty list to be appended to by the user
yourCities=[]

# Loop through based on the user's number of cities and add their city to their list
# x is the loop counter
x=1
while x<yourCityCount+1:
  # Get the name of the city
  city = raw_input("Enter your number " + str(x) + " favorite city: ")

  # Make sure it's not a duplicate. If it's not, add it to the list and increase the loop counter
  if city in yourCities:
    print "You already entered", city + "! Please try again."
  else:
    x+=1
    yourCities.append(city)

# Output the user's list of cities
print ""
print "You have",str(yourCityCount) + " favorite cities: "
print yourCities
print ""

# Compare the user's list of cities to see which cities are in common with my list
# Keep a count to display at the end
sameCities = set(yourCities).intersection(set(myCities))
sameCityCount = len(sameCities)

# Display the number of cities in common, with correct plural noun
if sameCityCount > 0:
  print "Cities we both like:", ", ".join(sameCities)
  if sameCityCount > 1:
    print "We have",str(sameCityCount) + " cities in common."
  else:
    print "We have",str(sameCityCount) + " city in common."
else:
  print "We have no cities in common."
  print ""

# Offer to delete a city. Only attempt if there are cities
if yourCityCount > 0:

  # Get the name of the city to delete
  cityToDelete = raw_input("Which city would you like to delete?: ")

  # Only proceed if the city is in the list
  if cityToDelete in yourCities:

    # If this item to delete, pop it
    yourCities.pop(yourCities.index(cityToDelete))

    # Print out the new list of cities
    print "I have deleted", cityToDelete + " from your list:", yourCities
  else:
    # Print an error message
    print "I couldn't find", cityToDelete + " in your list."

# Exit
raw_input ("Press Enter to Exit")