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

Input: Consider 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.

Output: 4

Input: Consider Input: Sentence: 'a basket that is full of fruits and vegetables'. How many words contain the letter 'v' in the sentence.

Output: 1

Input: Consider Input: Sentence: 'two trains sit side by side at a station'. How many words contain the letter 'a' in the sentence.
Output: 4