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.

[Q]: Sentence: 'a person walking on a street with a umbrella'. How many words start with the letter 's' in the sentence.
[A]: 1


[Q]: Sentence: 'woman riding on the back of a horse inside a building'. How many words start with the letter 'o' in the sentence.
[A]: 2


[Q]: Sentence: 'a woman takes a picture of herself in a restroom'. How many words start with the letter 'a' in the sentence.
[A]:
3