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 boy in a red baseball uniform throws a ball'. How many words start with the letter 'b' in the sentence.
Example Output: 3

Example Input: Sentence: 'a lit clock mounted on the side of a red building at night'. How many words start with the letter 'a' in the sentence.
Example Output: 3

Example Input: Sentence: 'a person using scissors to cut a piece of paper'. How many words start with the letter 'a' in the sentence.
Example Output:
2