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.

[EX Q]: Sentence: 'a person standing on a green field next to a river flying a kite'. How many words start with the letter 'a' in the sentence.
[EX A]: 4

[EX Q]: Sentence: 'some signs and the roof of a train station'. How many words start with the letter 'a' in the sentence.
[EX A]: 2

[EX Q]: Sentence: 'a toy horse sitting on a wooden table with an old poster in the background'. How many words start with the letter 'a' in the sentence.
[EX A]:
3