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 airplane sitting on a tarmac with work trucks close by'. How many words start with the letter 'a' in the sentence.
Example Output: 3

Example Input: Sentence: 'a black and white photo of a young man riding a horse'. How many words start with the letter 'a' in the sentence.
Example Output: 4

Example Input: Sentence: 'hospital display of different bed setups and a nurses uniform'. How many words start with the letter 'd' in the sentence.
Example Output:
2