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: 'two pizzas sitting on top of a pan on a counter'. How many words start with the letter 'p' in the sentence.
Example Output: 2

Example Input: Sentence: 'a man in vest and tie holding a cellphone'. How many words start with the letter 'a' in the sentence.
Example Output: 3

Example Input: Sentence: 'long legged birds in water and their reflections'. How many words start with the letter 'b' in the sentence.
Example Output:
1