Can I fix the index out of range error when I try to get a different word out of the last place of a list with all the same words

Question

For this exercise I can input words until i enter "stop". All the words that I have input will go in to a list. I use a for loop to loop over all the words in the list. If the word isnt the same as the next or previous I "mark" that word.If there are no marked words it wil print out that there are none.If there are 2 or more marked words it will print that it cant be known. This works well until the last word in the list is the "marked" one. I get the error list index out of range. Does anyone see a solution for this? Below I will paste the code.

Thank you!

woorden = []
woord = str(input())
vreemdeEend = 0
vreemdWoord = ""
while woord != "stop":
    woorden.append(woord)
    woord = str(input())

for index, elem in enumerate(woorden):
    if (woorden[index] != woorden[index-1] and woorden[index] != woorden[index+1] and woorden[index-1] != 0):
        vreemdeEend += 1
        vreemdWoord = woorden[index]

if(vreemdeEend == 1):
    print("De vreemde eend in de bijt is " + vreemdWoord)
elif(vreemdeEend >= 2):
    print("vreemd eend is onbeduid")
else:
    print("er is geen vreemd eend")`

I tried to check if the index is at the last place that it would check the previous 2 words to see if they are the same. But this didnt have any effect

Answer 1

woorden = []
woord = str(input())
vreemdeEend = 0
vreemdWoord = ""
while woord != "stop":
    woorden.append(woord)
    woord = str(input())

if len(woorden)>0:
    woorden.append(woorden[-1] + "DIFRENCE")

for index, elem in enumerate(woorden):
    if (woorden[index] != woorden[index-1] and woorden[index] != woorden[index+1] and woorden[index-1] != 0):
        vreemdeEend += 1
        vreemdWoord = woorden[index]

if(vreemdeEend == 1):
    print("De vreemde eend in de bijt is " + vreemdWoord)
elif(vreemdeEend >= 2):
    print("vreemd eend is onbeduid")
else:
    print("er is geen vreemd eend")`