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

Example Input: Sentence: 'young girls with backpacks are standing near stairs that look to go to the subway'. How many words contain the letter 'r' in the sentence.
Example Output: 4

Example Input: Sentence: 'a group of bears sitting next to each other on a sidewalk'. How many words contain the letter 't' in the sentence.
Example Output: 4

Example Input: Sentence: 'a close up of a knife next to a set of keys and a keyboard'. How many words contain the letter 'f' in the sentence.
Example Output:
3