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 kitchen with a sink and a dish rack'. How many words start with the letter 'a' in the sentence.
Example Output: 4

Example Input: Sentence: 'the man is laying in bed taking his temperature'. How many words start with the letter 'i' in the sentence.
Example Output: 2

Example Input: Sentence: 'an airplane as it is taking off and is ascending into space'. How many words start with the letter 'a' in the sentence.
Example Output:
5