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 group of people eating a meal outside'. How many words start with the letter 'g' in the sentence.
Example Output: 1

Example Input: Sentence: 'a person riding a skateboard down a street'. How many words start with the letter 'a' in the sentence.
Example Output: 3

Example Input: Sentence: 'a tennis player looking up and about to swing his racket'. How many words start with the letter 'u' in the sentence.
Example Output:
1