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 man riding a skateboard at a skate park'. How many words start with the letter 'r' in the sentence.
Example Output: 1

Example Input: Sentence: 'a bathroom has an overhead shower wand above the tub'. How many words start with the letter 't' in the sentence.
Example Output: 2

Example Input: Sentence: 'a man using a laptop computer on a table'. How many words start with the letter 'a' in the sentence.
Example Output:
3