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 living area with a couch coffee table and bookshelf'. How many words start with the letter 'l' in the sentence.
Example Output: 1

Example Input: Sentence: 'a woman walking up to a double decker bus that has stopped'. How many words start with the letter 'w' in the sentence.
Example Output: 2

Example Input: Sentence: 'this is a picture of a popular sking mountain'. How many words start with the letter 'a' in the sentence.
Example Output:
2