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 man standing outdoors next to a dirt bike and atv'. How many words start with the letter 't' in the sentence.
Example Output: 1

Example Input: Sentence: 'an older airplane flying above buildings and fields'. How many words start with the letter 'a' in the sentence.
Example Output: 4

Example Input: Sentence: 'two giraffes are walking down a rocky path'. How many words start with the letter 'a' in the sentence.
Example Output:
2