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 wearing a straw hat and a black shirt'. How many words start with the letter 'a' in the sentence.
Example Output: 4

Example Input: Sentence: 'someone flying a red kite in a crowded park'. How many words start with the letter 'a' in the sentence.
Example Output: 2

Example Input: Sentence: 'a person handing another person an object in the dark'. How many words start with the letter 'a' in the sentence.
Example Output:
3