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

Example Input: Sentence: 'a stop sign casting a shadow of a sign that says war'. How many words contain the letter 'y' in the sentence.
Example Output: 1

Example Input: Sentence: 'adults with helmets sitting on tricycles made for children'. How many words contain the letter 'r' in the sentence.
Example Output: 3

Example Input: Sentence: 'a train engine pulled into a station as passengers wait'. How many words contain the letter 'n' in the sentence.
Example Output:
5