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

Example Input: Sentence: 'a bird is standing on the edge of a book'. How many words contain the letter 'o' in the sentence.
Example Output: 3

Example Input: Sentence: 'this is a yellow train riding the rails'. How many words contain the letter 'n' in the sentence.
Example Output: 2

Example Input: Sentence: 'professional motorcycle racer leaning in to a curve'. How many words contain the letter 'n' in the sentence.
Example Output:
3