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

Sentence: 'an elephant standing in front of some trees with its trunk in the air'. How many words start with the letter 's' in the sentence.
2

Sentence: 'an airplane takes off against a gray sky'. How many words start with the letter 'a' in the sentence.

4