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 is carrying a large case with him'. How many words start with the letter 'w' in the sentence.
Example Output: 1

Example Input: Sentence: 'a man riding on top of a wave on a surfboard'. How many words start with the letter 'o' in the sentence.
Example Output: 3

Example Input: Sentence: 'a plain hotel bathroom is shown with a hair drier'. How many words start with the letter 'a' in the sentence.
Example Output:
2