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.

[EX Q]: Sentence: 'a person sitting on a stone wall using a cellular phone'. How many words start with the letter 's' in the sentence.
[EX A]: 2

[EX Q]: Sentence: 'a brown teddy bear is sitting on plaid sheets'. How many words start with the letter 'p' in the sentence.
[EX A]: 1

[EX Q]: Sentence: 'a person does a trick on a skateboard'. How many words start with the letter 'a' in the sentence.
[EX A]:
3