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 blue and white sign attached to a building'. How many words start with the letter 'a' in the sentence.
Example Output: 4

Example Input: Sentence: 'a golfer hitting a golf ball at a hole on the green'. How many words start with the letter 'g' in the sentence.
Example Output: 3

Example Input: Sentence: 'a small dog sits with its owner on a couch'. How many words start with the letter 'd' in the sentence.
Example Output:
1