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 stop sign and a no stopping sign are on a street corner'. How many words start with the letter 's' in the sentence.
Example Output: 5

Example Input: Sentence: 'a man holding a baby two women and two cakes'. How many words start with the letter 'a' in the sentence.
Example Output: 3

Example Input: Sentence: 'a pair of legs boxes and clothings laying on a bed with an opened closet in the background'. How many words start with the letter 'a' in the sentence.
Example Output:
4