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: '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

Example Input: Sentence: 'a group of boats floating in the ocean next to a dirty walkway'. How many words start with the letter 't' in the sentence.
Example Output: 2

Example Input: Sentence: 'a secluded road with light poles and sand from the side'. How many words start with the letter 's' in the sentence.
Example Output:
3