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 couple of people that are playing wii'. How many words start with the letter 'p' in the sentence.
Example Output: 2

Example Input: Sentence: 'person in profile and sunlight at a barred window'. How many words start with the letter 'a' in the sentence.
Example Output: 3

Example Input: Sentence: 'a man on a sidewalk standing next to a baby elephant'. How many words start with the letter 'a' in the sentence.
Example Output:
3