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: 'the pigeons are walking around in the park around the benches'. How many words start with the letter 'b' in the sentence.
Example Output: 1

Example Input: Sentence: 'group of zebras and gazelles grazing on the grass'. How many words start with the letter 'g' in the sentence.
Example Output: 4

Example Input: Sentence: 'a group of men are standing outside with tennis rackets'. How many words start with the letter 'o' in the sentence.
Example Output:
2