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

Ex Input:
Sentence: 'a man in mid swing of a baseball bat'. How many words contain the letter 'k' in the sentence.

Ex Output:
0

Ex Input:
Sentence: 'a large pizza smothered in cheese and sauce'. How many words contain the letter 'a' in the sentence.

Ex Output:
5

Ex Input:
Sentence: 'three mass transit trains underneath an overpass at a train stop'. How many words contain the letter 'i' in the sentence.

Ex Output:
3