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 fire hydrant beside a burned building in a city'. How many words start with the letter 'a' in the sentence.
Example Output: 3

Example Input: Sentence: 'post it notes scissors and glue stick on a table'. How many words start with the letter 's' in the sentence.
Example Output: 2

Example Input: Sentence: 'a man skiing in the snow on a sunny day'. How many words start with the letter 'a' in the sentence.
Example Output:
2