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 bunch of people in a metropolitan area with umbrellas walking on a sidewalk next to buildings'. How many words start with the letter 'p' in the sentence.
Example Output: 1

Example Input: Sentence: 'a baseball player gets ready to run to first base'. How many words start with the letter 't' in the sentence.
Example Output: 2

Example Input: Sentence: 'a card showing the right position to ride a horse'. How many words start with the letter 'r' in the sentence.
Example Output:
2