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

Example Input: Sentence: 'two men are flying kites in a field in front of a parking lot'. How many words start with the letter 'f' in the sentence.
Example Output: 3

Example Input: Sentence: 'a man sitting on a motorcycle at an intersection'. How many words start with the letter 's' in the sentence.
Example Output:
1