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 cat sitting on a pan in an oven'. How many words start with the letter 'a' in the sentence.
Example Output: 3

Example Input: Sentence: 'man in winter clothes riding a snowboard on a gentle slope'. How many words start with the letter 'g' in the sentence.
Example Output: 1

Example Input: Sentence: 'son enjoys the food his mother made for dinner'. How many words start with the letter 'f' in the sentence.
Example Output:
2