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

Ex Input:
Sentence: 'this bus waits at a bus station for passengers to board'. How many words contain the letter 'e' in the sentence.

Ex Output:
1

Ex 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.

Ex Output:
4

Ex Input:
Sentence: 'a tennis player getting ready to hit the ball'. How many words contain the letter 'r' in the sentence.

Ex Output:
2