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 little white airplane that is parked on some concrete'. How many words start with the letter 'p' in the sentence.
Example Output: 1

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: 'a zebra is standing beside a tree in the wild'. How many words start with the letter 'i' in the sentence.
Example Output:
2