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 couple of people that are playing wii'. How many words start with the letter 'p' in the sentence.
Example Output: 2

Example Input: Sentence: 'the zebra is walking through the tall brown grass'. How many words start with the letter 't' in the sentence.
Example Output: 4

Example Input: Sentence: 'the man is riding his bicycle on the sidewalk'. How many words start with the letter 's' in the sentence.
Example Output:
1