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 very cute long haired dog laying on a pillow'. How many words start with the letter 'v' in the sentence.
Example Output: 1

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: 'a woman standing at a bar preparing drink mix'. How many words start with the letter 'a' in the sentence.
Example Output:
3