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: 'the man is standing on a surfboard with a paddle'. How many words start with the letter 's' in the sentence.
Example Output: 2

Example Input: Sentence: 'a heard of sheep are grazing on the land'. How many words start with the letter 't' in the sentence.
Example Output: 1

Example Input: Sentence: 'a large jetliner flying through a crystal blue sky'. How many words start with the letter 'b' in the sentence.
Example Output:
1