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 man wearing a striped tie and a jacket'. How many words start with the letter 'j' in the sentence.
Example Output: 1

Example Input: Sentence: 'woman riding on the back of a horse inside a building'. How many words start with the letter 'o' in the sentence.
Example Output: 2

Example Input: Sentence: 'a baby laying inside of an open suitcase'. How many words start with the letter 'a' in the sentence.
Example Output:
2