In this task, you need to count the number of words in a sentence that contain the given letter

Example Input: Sentence: 'a man on a motorcycle towing another man on a skateboard'. How many words contain the letter 'n' in the sentence.
Example Output: 6

Example Input: Sentence: 'a person in the air with a skateboard upside down underneath'. How many words contain the letter 'i' in the sentence.
Example Output: 4

Example Input: Sentence: 'a number of people gathered at a birthday party'. How many words contain the letter 'i' in the sentence.
Example Output:
1