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 an orange jacket holds a blue and white tennis racket'. How many words start with the letter 'w' in the sentence.
Example Output: 1

Example Input: Sentence: 'a small bathroom has a mirror vanity and toilet'. How many words start with the letter 'b' in the sentence.
Example Output: 1

Example Input: Sentence: 'the clean keyboard is silver with white keys'. How many words start with the letter 'c' in the sentence.
Example Output:
1