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: 'several white boats are anchored at a marina'. How many words start with the letter 's' in the sentence.
Example Output: 1

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 towel that is on the glass of a shower'. How many words start with the letter 't' in the sentence.
Example Output:
3