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 pitching a baseball from a mound to a home plate'. How many words start with the letter 'a' in the sentence.
Example Output: 4

Example Input: Sentence: 'a boy waves at the camera standing on a tree stump'. How many words start with the letter 'a' in the sentence.
Example Output: 3

Example Input: Sentence: 'two women playing game with frisbee and red plastic cups'. How many words start with the letter 'c' in the sentence.
Example Output:
1