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.

Sentence: 'an officer sits on a brown horse on a city street'. How many words start with the letter 'o' in the sentence.
3

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

Sentence: 'a man in green feeding an elephant a bottle'. How many words start with the letter 'a' in the sentence.

3