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 guy squatting down and tapping his food with a woman sitting down'. How many words start with the letter 'f' in the sentence.
Example Output: 1

Example Input: Sentence: 'a group gathering in which several people are holding frisbees'. How many words start with the letter 'g' in the sentence.
Example Output: 2

Example Input: Sentence: 'a fire hydrant stands in front of a street and a citys night skyline with litup buildings'. How many words start with the letter 'f' in the sentence.
Example Output:
2