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

Input: Consider Input: Sentence: 'a gothic tower features a clock near a river'. How many words contain the letter 'e' in the sentence.

Output: 4

Input: Consider Input: Sentence: 'there are some warning signs on a public toilet'. How many words contain the letter 'a' in the sentence.

Output: 3

Input: Consider Input: Sentence: 'a mother and father walking with their son on a sandy beach'. How many words contain the letter 'n' in the sentence.
Output: 5