The function f(x) takes a string input and counts the number of vowels (a, e, i, o, u) in the string. It returns the count of vowels in the word form (e.g., "one", "two", "three").

[CODE]:
```python
def vowel_count(word: str) -> str:
    count = sum(1 for char in word.lower() if char in 'aeiou')
    word_form = {0: "zero", 1: "one", 2: "two", 3: "three", 4: "four", 5: "five"}
    return word_form.get(count, "undefined") if count in word_form else "undefined"

input_string = "example"
output = vowel_count(input_string)
print(output)
```