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 take out sandwich and two bottles of soda'. How many words start with the letter 'a' in the sentence.
Example Output: 2

Example Input: Sentence: 'a black bear walks in front of a tree in a forest'. How many words start with the letter 'a' in the sentence.
Example Output: 3

Example Input: Sentence: 'a boy is doing jumps on his skateboard at a skate park'. How many words start with the letter 's' in the sentence.
Example Output:
2