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: 'several people are playing frisbee in a park'. How many words start with the letter 'a' in the sentence.
Example Output: 2

Example Input: Sentence: 'a boy in a red baseball uniform throws a ball'. How many words start with the letter 'b' in the sentence.
Example Output: 3

Example Input: Sentence: 'a huge stainless steel cooking range with a hood in a salesroom'. How many words start with the letter 's' in the sentence.
Example Output:
3