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 smiling woman sits at a table with a pizza and salad'. How many words start with the letter 'a' in the sentence.
Example Output: 5

Example Input: Sentence: 'a picture of a zebra that is walking in the grass'. How many words start with the letter 'z' in the sentence.
Example Output: 1

Example Input: Sentence: 'a young child sits at the table and scoops food out of a can with a spoon'. How many words start with the letter 's' in the sentence.
Example Output:
3

