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: 'some black birds sitting on some rocks and some water'. How many words start with the letter 'b' in the sentence.
Example Output: 2

Example Input: Sentence: 'a young man holding a tennis racquet and its case'. How many words start with the letter 'h' in the sentence.
Example Output: 1

Example Input: Sentence: 'a group of men playing a game with nintendo wii controllers'. How many words start with the letter 'w' in the sentence.
Example Output:
2