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 train passes over a quiet city park on a bridge'. How many words start with the letter 'a' in the sentence.
Example Output: 3

Example Input: Sentence: 'a tall zebra grazing on a lush green field'. How many words start with the letter 't' in the sentence.
Example Output: 1

Example Input: Sentence: 'a person is taken in this very picture'. How many words start with the letter 'p' in the sentence.
Example Output:
2