In this task, you need to count the number of words in a sentence that start with the given letter. Answer with numbers and not words.

Example Input: Sentence: 'a giraffe and two small hogs stand in an enclosure'. How many words start with the letter 's' in the sentence.
Example Output: 2

Example Input: Sentence: 'a man in vest and tie holding a cellphone'. How many words start with the letter 'a' in the sentence.
Example Output: 3

Example Input: Sentence: 'a bed with a wire bed frame and a colorful bed spread'. How many words start with the letter 'a' in the sentence.
Example Output:
4