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 man holding a white frisbee while standing on top of a  beach'. How many words start with the letter 'o' in the sentence.
Example Output: 2

Example Input: Sentence: 'many different fruits and veggies are placed on a table'. How many words start with the letter 'a' in the sentence.
Example Output:
3