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

Ex Input:
Sentence: 'a beautiful old clock tower in a citys historic district'. How many words contain the letter 'a' in the sentence.

Ex Output:
3

Ex Input:
Sentence: 'a man on a motorcycle towing another man on a skateboard'. How many words contain the letter 'n' in the sentence.

Ex Output:
6

Ex Input:
Sentence: 'two marked cows stand upon mud and grass with tree filled hills in the background'. How many words contain the letter 'g' in the sentence.

Ex Output:
2