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 dog on one side of a glass door and a cat on the other side'. How many words start with the letter 'a' in the sentence.
[EX A]: 4

[EX Q]: Sentence: 'a couple of kids are sitting in the grass'. How many words start with the letter 'a' in the sentence.
[EX A]: 2

[EX Q]: Sentence: 'a woman holding a tennis racquet as a tennis ball approaches her'. How many words start with the letter 'r' in the sentence.
[EX A]:
1