##Write a program that continually prompts a user
##to enter in a series of first names. The user can
##elect to stop entering names when the supply the
##String "end". Store these first names in a list and
##print them out at the end of your program.
##Extension: prevent the user from entering duplicate names
##(hint: use the "in" operator)


names = []

name = input("enter a new name: ")

while name != "end":
    if name not in names:
        names.append(name)

    name = input("enter a new name: ")


print(names)