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 boy wearing blue has a skateboard in the air near a black railing'. How many words start with the letter 'a' in the sentence.
Example Output: 4

Example Input: Sentence: 'a large body of water with a boat on it'. How many words start with the letter 'o' in the sentence.
Example Output: 2

Example Input: Sentence: 'two lawn chairs with a bird perched on the back of one'. How many words start with the letter 'c' in the sentence.
Example Output:
1